First C-terminal Src homology 3 domain of SH3 and cysteine-rich domain-containing protein 3 (Stac3); Stac proteins are putative adaptor proteins that contain a cysteine-rich C1 domain and one or two SH3 domains at the C-terminus. There are three mammalian members (Stac1, Stac2, and Stac3) of this family. Stac1 and Stac3 contain two SH3 domains while Stac2 contains a single SH3 domain at the C-terminus. Stac1 and Stac2 have been found to be expressed differently in mature dorsal root ganglia (DRG) neurons. Stac1 is mainly expressed in peptidergic neurons while Stac2 is found in a subset of nonpeptidergic and all trkB+ neurons. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFIIR 299
Cdd:cd11986    1 YFVALYRFKALEKDDLDFHPGERITVIDDSNEEWWRGKIGEKTGYFPMNFIIR 53

Unstructured on SH3 and cysteine-rich domain-containing protein 2; STAC2_u1 is a region of natively unstructured but highly conserved sequence between C1_1 pfam00130, and an SH3 domain, eg pfam00018, on SH3 and cysteine-rich domain-containing proteins from higher eukaryotes. The function is not known.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 568967547  146 GFRRAYSSPLYSDQQYAV-------SAANRNDPVFETLRVGVIMANKERKKGQADKKNPLAAMMEEEPESARPEEGKS 216
Cdd:pfam16664   2 AFRRNFSSPLLIEDQLGVvkevppaAGNKKVDPVYEALRYGTSLAQMSRSSFGSSSESPTRSLHESREELEDKQSSPS 79

First C-terminal Src homology 3 domain of SH3 and cysteine-rich domain-containing protein 3 (Stac3); Stac proteins are putative adaptor proteins that contain a cysteine-rich C1 domain and one or two SH3 domains at the C-terminus. There are three mammalian members (Stac1, Stac2, and Stac3) of this family. Stac1 and Stac3 contain two SH3 domains while Stac2 contains a single SH3 domain at the C-terminus. Stac1 and Stac2 have been found to be expressed differently in mature dorsal root ganglia (DRG) neurons. Stac1 is mainly expressed in peptidergic neurons while Stac2 is found in a subset of nonpeptidergic and all trkB+ neurons. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFIIR 299
Cdd:cd11986    1 YFVALYRFKALEKDDLDFHPGERITVIDDSNEEWWRGKIGEKTGYFPMNFIIR 53

Src homology 3 domains; Src homology 3 (SH3) domains bind to target proteins through sequences containing proline and hydrophobic amino acids. Pro-containing polypeptides may bind to SH3 domains in 2 different binding orientations.

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|....*
gi 568967547   244 QSHYFVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIG-EKVGFFPPNFI 297
Cdd:smart00326   1 EGPQVRALYDYTAQDPDELSFKKGDIITVLEKSDDGWWKGRLGrGKEGLFPSNYV 55

Phorbol esters/diacylglycerol binding domain (C1 domain); This domain is also known as the Protein kinase C conserved region 1 (C1) domain.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 568967547   89 HKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYV 134
Cdd:pfam00130   1 HHFVHRNFKQPTFCDHCGEFLWGLGKQGLKCSWCKLNVHKRCHEKV 46

Variant SH3 domain; SH3 (Src homology 3) domains are often indicative of a protein involved in signal transduction related to cytoskeletal organization. First described in the Src cytoplasmic tyrosine kinase. The structure is a partly opened beta barrel.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 568967547  306 VHRVTRSFVGNREIGqITLKKDQIVVQKGDEAGGYVKVYTGRKVGLFPTDFLEEI 360
Cdd:pfam07653   1 YGRVIFDYVGTDKNG-LTLKKGDVVKVLGKDNDGWWEGETGGRVGLVPSTAVEEI 54

First C-terminal Src homology 3 domain of SH3 and cysteine-rich domain-containing protein 3 (Stac3); Stac proteins are putative adaptor proteins that contain a cysteine-rich C1 domain and one or two SH3 domains at the C-terminus. There are three mammalian members (Stac1, Stac2, and Stac3) of this family. Stac1 and Stac3 contain two SH3 domains while Stac2 contains a single SH3 domain at the C-terminus. Stac1 and Stac2 have been found to be expressed differently in mature dorsal root ganglia (DRG) neurons. Stac1 is mainly expressed in peptidergic neurons while Stac2 is found in a subset of nonpeptidergic and all trkB+ neurons. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFIIR 299
Cdd:cd11986    1 YFVALYRFKALEKDDLDFHPGERITVIDDSNEEWWRGKIGEKTGYFPMNFIIR 53

Second C-terminal Src homology 3 domain of SH3 and cysteine-rich domain-containing proteins 1 and 3; This model represents the second C-terminal SH3 domain of Stac1 and Stac3. Stac proteins are putative adaptor proteins that contain a cysteine-rich C1 domain and one or two SH3 domains at the C-terminus. There are three mammalian members (Stac1, Stac2, and Stac3) of this family. Stac1 and Stac3 contain two SH3 domains while Stac2 contains a single SH3 domain at the C-terminus. Stac1 and Stac2 have been found to be expressed differently in mature dorsal root ganglia (DRG) neurons. Stac1 is mainly expressed in peptidergic neurons while Stac2 is found in a subset of nonpeptidergic and all trkB+ neurons. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 568967547 306 VHRVTRSFVGNREIGQITLKKDQIVVQKGDEAGGYVKVYTGRKVGLFPTDF 356
Cdd:cd11834    1 VHRVTRSFVGNKEIGQITLKKDQIVVQKGEEQNGYIKVYTGRKVGLFPLDF 51

C-terminal Src homology 3 domain of SH3 and cysteine-rich domain-containing protein 2 (Stac2); Stac proteins are putative adaptor proteins that contain a cysteine-rich C1 domain and one or two SH3 domains at the C-terminus. There are three mammalian members (Stac1, Stac2, and Stac3) of this family. Stac2 contains a single SH3 domain at the C-terminus unlike Stac1 and Stac3, which contain two C-terminal SH3 domains. Stac1 and Stac2 have been found to be expressed differently in mature dorsal root ganglia (DRG) neurons. Stac1 is mainly expressed in peptidergic neurons while Stac2 is found in a subset of nonpeptidergic and all trkB+ neurons. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 568967547 248 FVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFIIR 299
Cdd:cd11985    2 YVALYKFLPQENNDLPLQPGDRVMVVDDSNEDWWKGKSGDRVGFFPANFVQR 53

protein kinase C conserved region 1 (C1 domain) found in SH3 and cysteine-rich domain-containing protein 2 (Stac2) and similar proteins; Stac2, also called 24b2/Stac2, or Src homology 3 and cysteine-rich domain-containing protein 2, plays a redundant role in promoting the expression of calcium channel CACNA1S at the cell membrane, and thereby contributes to increased channel activity. It slows down the inactivation rate of the calcium channel CACNA1C. Stac2 contains a cysteine-rich C1 domain and one SH3 domain at the C-terminus. This model corresponds to the C1 domain. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*.
gi 568967547  87 KPHKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYVEMQRCFGK 142
Cdd:cd20881    4 RTHSFQEHVFKKPSPCELCHQMIVGNSKQGLRCKMCKVSVHLWCSEEVSHQQCTGK 59

Src Homology 3 domain superfamily; Src Homology 3 (SH3) domains are protein interaction domains that bind proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. Thus, they are referred to as proline-recognition domains (PRDs). SH3 domains are less selective and show more diverse specificity compared to other PRDs. They have been shown to bind peptide sequences that lack the PxxP motif; examples include the PxxDY motif of Eps8 and the RKxxYxxY sequence in SKAP55. SH3 domain containing proteins play versatile and diverse roles in the cell, including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies, among others. Many members of this superfamily are adaptor proteins that associate with a number of protein partners, facilitating complex formation and signal transduction.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKI-GEKVGFFPPNF 296
Cdd:cd00174    1 YARALYDYEAQDDDELSFKKGDIITVLEKDDDGWWEGELnGGREGLFPANY 51

Src homology 3 domain of Ysc84p and similar fungal proteins; This family is composed of the Saccharomyces cerevisiae proteins, Ysc84p (also called LAS17-binding protein 4, Lsb4p) and Lsb3p, and similar fungal proteins. They contain an N-terminal SYLF domain (also called DUF500) and a C-terminal SH3 domain. Ysc84p localizes to actin patches and plays an important in actin polymerization during endocytosis. The N-terminal domain of both Ysc84p and Lsb3p can bind and bundle actin filaments. A study of the yeast SH3 domain interactome predicts that the SH3 domains of Lsb3p and Lsb4p may function as molecular hubs for the assembly of endocytic complexes. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVID--DSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11842    1 KAVALYDFAGEQPGDLAFQKGDIITILKksDSQNDWWTGRIGGREGIFPANYV 53

Src homology 3 domain of Signal Transducing Adaptor Molecule 1; STAM1 is part of the endosomal sorting complex required for transport (ESCRT-0) and is involved in sorting ubiquitinated cargo proteins from the endosome. It may also be involved in the regulation of IL2 and GM-CSF mediated signaling, and has been implicated in neural cell survival. STAMs were discovered as proteins that are highly phosphorylated following cytokine and growth factor stimulation. They function in cytokine signaling and surface receptor degradation, as well as regulate Golgi morphology. They associate with many proteins including Jak2 and Jak3 tyrosine kinases, Hrs, AMSH, and UBPY. STAM adaptor proteins contain VHS (Vps27, Hrs, STAM homology), ubiquitin interacting (UIM), and SH3 domains. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*...
gi 568967547 250 ALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11964    5 AIYDFEAAEDNELTFKAGDIITILDDSDPNWWKGETPQGTGLFPSNFV 52

Src homology 3 domain of Signal Transducing Adaptor Molecule 2; STAM2, also called EAST (Epidermal growth factor receptor-associated protein with SH3 and TAM domain) or Hbp (Hrs binding protein), is part of the endosomal sorting complex required for transport (ESCRT-0). It plays a role in sorting mono-ubiquinated endosomal cargo for trafficking to the lysosome for degradation. It is also involved in the regulation of exocytosis. STAMs were discovered as proteins that are highly phosphorylated following cytokine and growth factor stimulation. They function in cytokine signaling and surface receptor degradation, as well as regulate Golgi morphology. They associate with many proteins including Jak2 and Jak3 tyrosine kinases, Hrs, AMSH, and UBPY. STAM adaptor proteins contain VHS (Vps27, Hrs, STAM homology), ubiquitin interacting (UIM), and SH3 domains. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*...
gi 568967547 250 ALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11963    6 ALYDFEAVEDNELTFKHGEIIIVLDDSDANWWKGENHRGVGLFPSNFV 53

second protein kinase C conserved region 1 (C1 domain) found in classical (or conventional) protein kinase C (cPKC), novel protein kinase C (nPKC), and similar proteins; PKCs are classified into three groups (classical, atypical, and novel) depending on their mode of activation and the structural characteristics of their regulatory domain. PKCs undergo three phosphorylations in order to take mature forms. In addition, cPKCs depend on calcium, DAG (1,2-diacylglycerol), and in most cases, phosphatidylserine (PS) for activation. nPKCs are calcium-independent, but require DAG and PS for activity, while atypical PKCs (aPKCs) only require PS. PKCs phosphorylate and modify the activities of a wide variety of cellular proteins including receptors, enzymes, cytoskeletal proteins, transcription factors, and other kinases. They play a central role in signal transduction pathways that regulate cell migration and polarity, proliferation, differentiation, and apoptosis. This family includes classical PKCs (cPKCs) and novel PKCs (nPKCs). There are four cPKC isoforms (named alpha, betaI, betaII, and gamma) and four nPKC isoforms (delta, epsilon, eta, and theta). Members of this family contain two copies of C1 domain. This model corresponds to the second one. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*.
gi 568967547  89 HKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYV 134
Cdd:cd20793    1 HKFKVHTYYSPTFCDHCGSLLYGLVRQGLKCKDCGMNVHHRCKENV 46

Phorbol esters/diacylglycerol binding domain (C1 domain); This domain is also known as the Protein kinase C conserved region 1 (C1) domain.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*.
gi 568967547   89 HKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYV 134
Cdd:pfam00130   1 HHFVHRNFKQPTFCDHCGEFLWGLGKQGLKCSWCKLNVHKRCHEKV 46

C-terminal Src homology 3 domain of Growth factor receptor-bound protein 2 (GRB2) and related proteins; This family includes the adaptor protein GRB2 and related proteins including Drosophila melanogaster Downstream of receptor kinase (DRK), Caenorhabditis elegans Sex muscle abnormal protein 5 (Sem-5), GRB2-related adaptor protein (GRAP), GRAP2, and similar proteins. Family members contain an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. GRB2/Sem-5/DRK is a critical signaling molecule that regulates the Ras pathway by linking tyrosine kinases to the Ras guanine nucleotide releasing protein Sos (son of sevenless), which converts Ras to the active GTP-bound state. GRAP2 plays an important role in T cell receptor (TCR) signaling by promoting the formation of the SLP-76:LAT complex, which couples the TCR to the Ras pathway. GRAP acts as a negative regulator of T cell receptor (TCR)-induced lymphocyte proliferation by downregulating the signaling to the Ras/ERK pathway. The C-terminal SH3 domains (SH3c) of GRB2 and GRAP2 have been shown to bind to classical PxxP motif ligands, as well as to non-classical motifs. GRB2 SH3c binds Gab2 (Grb2-associated binder 2) through epitopes containing RxxK motifs, while the SH3c of GRAP2 binds to the phosphatase-like protein HD-PTP via a RxxxxK motif. SH3 domains are protein interaction domains that typically bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 568967547 250 ALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFIIR 299
Cdd:cd11805    4 ALYDFNPQEPGELEFRRGDIITVLDSSDPDWWKGELRGRVGIFPANYVQP 53

Fifth Src homology 3 domain (or SH3E) of Intersectin; Intersectins (ITSNs) are adaptor proteins that function in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. They are essential for initiating clathrin-coated pit formation. They bind to many proteins through their multidomain structure and facilitate the assembly of multimeric complexes. Vertebrates contain two ITSN proteins, ITSN1 and ITSN2, which exist in alternatively spliced short and long isoforms. The short isoforms contain two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoforms, in addition, contain RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. ITSN1 and ITSN2 are both widely expressed, with variations depending on tissue type and stage of development. The fifth SH3 domain (or SH3E) of ITSN1 has been shown to bind many protein partners including SGIP1, Sos1, dynamin1/2, CIN85, c-Cbl, SHIP2, N-WASP, and synaptojanin-1, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*....
gi 568967547 249 VALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11840    3 IALFPYTAQNEDELSFQKGDIINVLSKDDPDWWRGELNGQTGLFPSNYV 51

Second Src Homology 3 domain (SH3B) of CD2-associated protein and similar proteins; This subfamily is composed of the second SH3 domain (SH3B) of CD2AP, CIN85 (Cbl-interacting protein of 85 kDa), and similar domains. CD2AP and CIN85 are adaptor proteins that bind to protein partners and assemble complexes that have been implicated in T cell activation, kidney function, and apoptosis of neuronal cells. They also associate with endocytic proteins, actin cytoskeleton components, and other adaptor proteins involved in receptor tyrosine kinase (RTK) signaling. CD2AP and the main isoform of CIN85 contain three SH3 domains, a proline-rich region, and a C-terminal coiled-coil domain. All of these domains enable CD2AP and CIN85 to bind various protein partners and assemble complexes that have been implicated in many different functions. SH3B of both proteins have been shown to bind to Cbl. In the case of CD2AP, its SH3B binds to Cbl at a site distinct from the c-Cbl/SH3A binding site. The CIN85 SH3B also binds ubiquitin. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*...
gi 568967547 250 ALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11874    4 VLFSYTPQNEDELELKVGDTIEVLGEVEEGWWEGKLNGKVGVFPSNFV 51

Fourth Src homology 3 domain of ADAM-binding protein Eve-1; Eve-1, also called SH3 domain-containing protein 19 (SH3D19) or EEN-binding protein (EBP), exists in multiple alternatively spliced isoforms. The longest isoform contains five SH3 domain in the C-terminal region and seven proline-rich motifs in the N-terminal region. It is abundantly expressed in skeletal muscle and heart, and may be involved in regulating the activity of ADAMs (A disintegrin and metalloproteases). Eve-1 interacts with EEN, an endophilin involved in endocytosis and may be the target of the MLL-EEN fusion protein that is implicated in leukemogenesis. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*...
gi 568967547 249 VALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNF 296
Cdd:cd11817    3 VALYDFTGETEEDLSFQRGDRILVTEHLDAEWSRGRLNGREGIFPRAF 50

Third Src homology 3 domain (or SH3C) of Intersectin; Intersectins (ITSNs) are adaptor proteins that function in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. They are essential for initiating clathrin-coated pit formation. They bind to many proteins through their multidomain structure and facilitate the assembly of multimeric complexes. Vertebrates contain two ITSN proteins, ITSN1 and ITSN2, which exist in alternatively spliced short and long isoforms. The short isoforms contain two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoforms, in addition, contain RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. ITSN1 and ITSN2 are both widely expressed, with variations depending on tissue type and stage of development. The third SH3 domain (or SH3C) of ITSN1 has been shown to bind many proteins including dynamin1/2, CIN85, c-Cbl, SHIP2, Reps1, synaptojanin-1, and WNK, among others. The SH3C of ITSN2 has been shown to bind the K15 protein of Kaposi's sarcoma-associated herpesvirus. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVIDDSNEeWWRGKIGEKVGFFPPNFI 297
Cdd:cd11838    1 EYIALYPYESNEPGDLTFNAGDVILVTKKDGE-WWTGTIGDRTGIFPSNYV 50

Src Homology 3 domain of Tec-like Protein Tyrosine Kinases; The Tec (Tyrosine kinase expressed in hepatocellular carcinoma) subfamily is composed of Tec, Btk, Bmx (Etk), Itk (Tsk, Emt), Rlk (Txk), and similar proteins. They are cytoplasmic (or nonreceptor) tyr kinases containing Src homology protein interaction domains (SH3, SH2) N-terminal to the catalytic tyr kinase domain. Most Tec subfamily members (except Rlk) also contain an N-terminal pleckstrin homology (PH) domain, which binds the products of PI3K and allows membrane recruitment and activation. In addition, some members contain the Tec homology (TH) domain, which contains proline-rich and zinc-binding regions. Tec kinases are expressed mainly by haematopoietic cells, although Tec and Bmx are also found in endothelial cells. B-cells express Btk and Tec, while T-cells express Itk, Txk, and Tec. Collectively, Tec kinases are expressed in a variety of myeloid cells such as mast cells, platelets, macrophages, and dendritic cells. Each Tec kinase shows a distinct cell-type pattern of expression. The function of Tec kinases in lymphoid cells have been studied extensively. They play important roles in the development, differentiation, maturation, regulation, survival, and function of B-cells and T-cells. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 568967547 249 VALYRFKALEKDDLDFPPGEKITVIDDSNEEWW--RGKIGEkVGFFPPNFI 297
Cdd:cd11768    3 VALYDFQPIEPGDLPLEKGEEYVVLDDSNEHWWraRDKNGN-EGYIPSNYV 52

Third Src homology 3 domain (or SH3C) of Intersectin-2; Intersectin-2 (ITSN2) is an adaptor protein that functions in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. It plays a role in clathrin-coated pit (CCP) formation. It binds to many proteins through its multidomain structure and facilitate the assembly of multimeric complexes. ITSN2 also functions as a specific GEF for Cdc42 activation in epithelial morphogenesis, and is required in mitotic spindle orientation. It exists in alternatively spliced short and long isoforms. The short isoform contains two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoform, in addition, contains RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. The third SH3 domain (SH3C) of ITSN2 has been shown to bind the K15 protein of Kaposi's sarcoma-associated herpesvirus. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 568967547 248 FVALYRFKALEKDDLDFPPGEKITVIDDSNEeWWRGKIGEKVGFFPPNFI 297
Cdd:cd11992    2 YIALYPYSSSEPGDLTFNEGEEILVTQKDGE-WWTGSIEDRTGIFPSNYV 50

Third Src homology 3 domain (or SH3C) of Intersectin-1; Intersectin-1 (ITSN1) is an adaptor protein that functions in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. It plays a role in clathrin-coated pit (CCP) formation. It binds to many proteins through its multidomain structure and facilitate the assembly of multimeric complexes. ITSN1 localizes in membranous organelles, CCPs, the Golgi complex, and may be involved in the cell membrane trafficking system. It exists in alternatively spliced short and long isoforms. The short isoform contains two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoform, in addition, contains RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. The third SH3 domain (or SH3C) of ITSN1 has been shown to bind many proteins including dynamin1/2, CIN85, c-Cbl, SHIP2, Reps1, synaptojanin-1, and WNK, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 568967547 248 FVALYRFKALEKDDLDFPPGEKITVIDDSNEeWWRGKIGEKVGFFPPNFI 297
Cdd:cd11991    2 YVAMYTYESNEQGDLTFQQGDVILVTKKDGD-WWTGTVGDKTGVFPSNYV 50

Src homology 3 domain of Src kinase-like Protein Tyrosine Kinases; Src subfamily members include Src, Lck, Hck, Blk, Lyn, Fgr, Fyn, Yrk, Yes, and Brk. Src (or c-Src) proteins are cytoplasmic (or non-receptor) PTKs which are anchored to the plasma membrane. They contain an N-terminal SH4 domain with a myristoylation site, followed by SH3 and SH2 domains, a tyr kinase domain, and a regulatory C-terminal region containing a conserved tyr. They are activated by autophosphorylation at the tyr kinase domain, but are negatively regulated by phosphorylation at the C-terminal tyr by Csk (C-terminal Src Kinase). However, Brk lacks the N-terminal myristoylation sites. Src proteins are involved in signaling pathways that regulate cytokine and growth factor responses, cytoskeleton dynamics, cell proliferation, survival, and differentiation. They were identified as the first proto-oncogene products, and they regulate cell adhesion, invasion, and motility in cancer cells, and tumor vasculature, contributing to cancer progression and metastasis. Src kinases are overexpressed in a variety of human cancers, making them attractive targets for therapy. They are also implicated in acute inflammatory responses and osteoclast function. Src, Fyn, Yes, and Yrk are widely expressed, while Blk, Lck, Hck, Fgr, Lyn, and Brk show a limited expression pattern. This subfamily also includes Drosophila Src42A, Src oncogene at 42A (also known as Dsrc41) which accumulates at sites of cell-cell or cell-matrix adhesion, and participates in Drosphila development and wound healing. It has been shown to promote tube elongation in the tracheal system, is essential for proper cell-cell matching during dorsal closure, and regulates cell-cell contacts in developing Drosophila eyes. The SH3 domain of Src kinases contributes to substrate recruitment by binding adaptor proteins/substrates, and regulation of kinase activity through an intramolecular interaction. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 568967547 248 FVALYRFKALEKDDLDFPPGEKITVIDDSNEEWW--RGKIGEKVGFFPPNF 296
Cdd:cd11845    2 YVALYDYEARTDDDLSFKKGDRLQILDDSDGDWWlaRHLSTGKEGYIPSNY 52

second protein kinase C conserved region 1 (C1 domain) found in Caenorhabditis elegans serine/threonine-protein kinase DKF-1 and similar proteins; DKF-1 converts transient diacylglycerol (DAG) signals into prolonged physiological effects, independently of PKC. It plays a role in the regulation of growth and neuromuscular control of movement. It is involved in immune response to Staphylococcus aureus bacterium by activating transcription factor hlh-30 downstream of phospholipase plc-1. Members of this group contain two copies of the C1 domain. This model corresponds to the second one. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*....
gi 568967547  88 PHKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYVEM 136
Cdd:cd20798    1 PHTLAEHNYKKPTVCKVCDKLLVGLVRQGLKCRDCGVNVHKKCASLLPS 49

C-terminal (or second) Src Homology 3 domain of the p67phox subunit of NADPH oxidase; p67phox, also called Neutrophil cytosol factor 2 (NCF-2), is a cytosolic subunit of the phagocytic NADPH oxidase complex (also called Nox2 or gp91phox) which plays a crucial role in the cellular response to bacterial infection. NADPH oxidase catalyzes the transfer of electrons from NADPH to oxygen during phagocytosis forming superoxide and reactive oxygen species. p67phox plays a regulatory role and contains N-terminal TPR, first SH3 (or N-terminal or central SH3), PB1, and C-terminal SH3 domains. It binds, via its C-terminal SH3 domain, to a proline-rich region of p47phox and upon activation, this complex assembles with flavocytochrome b558, the Nox2-p22phox heterodimer. Concurrently, RacGTP translocates to the membrane and interacts with the TPR domain of p67phox, which leads to the activation of NADPH oxidase. The PB1 domain of p67phox binds to its partner PB1 domain in p40phox, and this facilitates the assembly of p47phox-p67phox at the membrane. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd12046    1 QVVALFSYEASQPEDLEFQKGDVILVLSKVNEDWLEGQCKGKIGIFPSAFV 51

protein kinase C conserved region 1 (C1 domain) found in uncharacterized proteins similar to myotubularin-related proteins; The family includes a group of uncharacterized proteins that show high sequence similarity to vertebrate myotubularin-related proteins (MTMRs), such as MTMR5 and MTMR13. MTMRs may function as guanine nucleotide exchange factors (GEFs). Vertebrate MTMR5 and MTMR13 contain an N-terminal DENN domain, a PH-GRAM domain, an inactive PTP domain, a SET interaction domain, a coiled-coil domain, and a C-terminal PH domain. Members of this family contain these domains and have an additional C1 domain. This model corresponds to the C1 domain. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 568967547  88 PHKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYVEMQ 137
Cdd:cd20828    5 PHNFEPHSFVTPTNCDYCLQILWGIVKKGMKCSECGYNCHEKCQPQVPKQ 54

protein kinase C conserved region 1 (C1 domain) found in RAS guanyl-releasing protein 4 (RASGRP4) and similar proteins; RASGRP4 functions as a cation- and diacylglycerol (DAG)-regulated nucleotide exchange factor activating Ras through the exchange of bound GDP for GTP. It may function in mast cell differentiation. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 568967547  88 PHKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYVEMQ 137
Cdd:cd20863    3 LHNFHETTFKKPTFCDSCSGFLWGVTKQGYRCQDCGINCHKHCKDQVDVE 52

Third Src homology 3 domain of ADAM-binding protein Eve-1; Eve-1, also called SH3 domain-containing protein 19 (SH3D19) or EEN-binding protein (EBP), exists in multiple alternatively spliced isoforms. The longest isoform contains five SH3 domain in the C-terminal region and seven proline-rich motifs in the N-terminal region. It is abundantly expressed in skeletal muscle and heart, and may be involved in regulating the activity of ADAMs (A disintegrin and metalloproteases). Eve-1 interacts with EEN, an endophilin involved in endocytosis and may be the target of the MLL-EEN fusion protein that is implicated in leukemogenesis. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*....
gi 568967547 249 VALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11816    3 VARFDFEGEQEDELSFSEGDVITLKEYVGEEWAKGELNGKIGIFPLNFV 51

Src homology 3 domains of the p47phox subunit of NADPH oxidase and similar domains; This family is composed of the tandem SH3 domains of p47phox subunit of NADPH oxidase and Nox Organizing protein 1 (NoxO1), the four SH3 domains of Tks4 (Tyr kinase substrate with four SH3 domains), the five SH3 domains of Tks5, the SH3 domain of obscurin, Myosin-I, and similar domains. Most members of this group also contain Phox homology (PX) domains, except for obscurin and Myosin-I. p47phox and NoxO1 are regulators of the phagocytic NADPH oxidase complex (also called Nox2 or gp91phox) and nonphagocytic NADPH oxidase Nox1, respectively. They play roles in the activation of their respective NADPH oxidase, which catalyzes the transfer of electrons from NADPH to molecular oxygen to form superoxide. Tks proteins are Src substrates and scaffolding proteins that play important roles in the formation of podosomes and invadopodia, the dynamic actin-rich structures that are related to cell migration and cancer cell invasion. Obscurin is a giant muscle protein that plays important roles in the organization and assembly of the myofibril and the sarcoplasmic reticulum. Type I myosins (Myosin-I) are actin-dependent motors in endocytic actin structures and actin patches. They play roles in membrane traffic in endocytic and secretory pathways, cell motility, and mechanosensing. Myosin-I contains an N-terminal actin-activated ATPase, a phospholipid-binding TH1 (tail homology 1) domain, and a C-terminal extension which includes an F-actin-binding TH2 domain, an SH3 domain, and an acidic peptide that participates in activating the Arp2/3complex. The SH3 domain of myosin-I is required for myosin-I-induced actin polymerization. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 568967547 248 FVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11856    2 YVAIADYEAQGDDEISLQEGEVVEVLEKNDSGWWYVRKGDKEGWVPASYL 51

Src homology 3 domain of Rho GTPase-activating proteins 32 and 33, and similar proteins; Members of this family contain N-terminal PX and Src Homology 3 (SH3) domains, a central Rho GAP domain, and C-terminal extensions. RhoGAPs (or ARHGAPs) bind to Rho proteins and enhance the hydrolysis rates of bound GTP. ARHGAP32 is also called RICS, PX-RICS, p250GAP, or p200RhoGAP. It is a Rho GTPase-activating protein for Cdc42 and Rac1, and is implicated in the regulation of postsynaptic signaling and neurite outgrowth. PX-RICS, a variant of RICS that contain PX and SH3 domains, is the main isoform expressed during neural development. It is involved in neural functions including axon and dendrite extension, postnatal remodeling, and fine-tuning of neural circuits during early brain development. ARHGAP33, also called sorting nexin 26 or TCGAP (Tc10/CDC42 GTPase-activating protein), is widely expressed in the brain where it is involved in regulating the outgrowth of axons and dendrites and is regulated by the protein tyrosine kinase Fyn. It is translocated to the plasma membrane in adipocytes in response to insulin and may be involved in the regulation of insulin-stimulated glucose transport. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....
gi 568967547 253 RFKALEKDDLDFPPGEKITVID-DSNEE--WWRGKIGEKVGFFP 293
Cdd:cd11835    7 RYTAQAPDELSLEVGDIVSVIDmPPPEEstWWRGKKGFQVGFFP 50

C-terminal Src homology 3 domain of GRB2-related adaptor protein; GRAP is a GRB-2 like adaptor protein that is highly expressed in lymphoid tissues. It acts as a negative regulator of T cell receptor (TCR)-induced lymphocyte proliferation by downregulating the signaling to the Ras/ERK pathway. It has been identified as a regulator of TGFbeta signaling in diabetic kidney tubules and may have a role in the pathogenesis of the disease. GRAP contains an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. The C-terminal SH3 domains (SH3c) of the related proteins, GRB2 and GRAP2, have been shown to bind to classical PxxP motif ligands, as well as to non-classical motifs. GRB2 SH3c binds Gab2 (Grb2-associated binder 2) through epitopes containing RxxK motifs, while the SH3c of GRAP2 binds to the phosphatase-like protein HD-PTP via a RxxxxK motif. SH3 domains are protein interaction domains that typically bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11951    1 FVQAQYDFSAEDPSQLSFRRGDIIEVLDCPDPNWWRGRISGRVGFFPRNYV 51

first protein kinase C conserved region 1 (C1 domain) found in Caenorhabditis elegans serine/threonine-protein kinase DKF-1 and similar proteins; DKF-1 converts transient diacylglycerol (DAG) signals into prolonged physiological effects, independently of PKC. It plays a role in the regulation of growth and neuromuscular control of movement. It is involved in immune response to Staphylococcus aureus bacterium by activating transcription factor hlh-30 downstream of phospholipase plc-1. Members of this group contain two copies of the C1 domain. This model corresponds to the first one. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*
gi 568967547  86 DKPHKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHC 130
Cdd:cd20797    1 TRPHVVEVEQYMTPTFCDYCGEMLTGLMKQGVKCKNCRCNFHKRC 45

second protein kinase C conserved region 1 (C1 domain) found in the classical (or conventional) protein kinase C (cPKC) family; PKCs are classified into three groups (classical, atypical, and novel) depending on their mode of activation and the structural characteristics of their regulatory domain. cPKCs are potent kinases for histones, myelin basic protein, and protamine. They depend on calcium, DAG (1,2-diacylglycerol), and in most cases, phosphatidylserine (PS) for activation. There are four cPKC isoforms, named alpha, betaI, betaII, and gamma. PKC-alpha is expressed in many tissues and is associated with cell proliferation, apoptosis, and cell motility. It plays a role in the signaling of the growth factors PDGF, VEGF, EGF, and FGF. Abnormal levels of PKC-alpha have been detected in many transformed cell lines and several human tumors. In addition, PKC-alpha is required for HER2 dependent breast cancer invasion. The PKC beta isoforms (I and II), generated by alternative splicing of a single gene, are preferentially activated by hyperglycemia-induced DAG (1,2-diacylglycerol) in retinal tissues. This is implicated in diabetic microangiopathy such as ischemia, neovascularization, and abnormal vasodilator function. PKC-beta also plays an important role in VEGF signaling. In addition, glucose regulates proliferation in retinal endothelial cells via PKC-betaI. PKC-beta is also being explored as a therapeutic target in cancer. It contributes to tumor formation and is involved in the tumor host mechanisms of inflammation and angiogenesis. PKC-gamma is mainly expressed in neuronal tissues. It plays a role in protection from ischemia. Members of this family contain two copies of C1 domain. This model corresponds to the second one. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*.
gi 568967547  89 HKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYV 134
Cdd:cd20836    1 HKFKVHTYSSPTFCDHCGSLLYGLIHQGMKCDTCDMNVHKRCVKNV 46

protein kinase C conserved region 1 (C1 domain) found in the RAS guanyl-releasing protein (RASGRP) family; The RASGRP family includes RASGRP1-4. They function as cation-, usually calcium-, and diacylglycerol (DAG)-regulated nucleotide exchange factor activating Ras through the exchange of bound GDP for GTP. RASGRP1, also called calcium and DAG-regulated guanine nucleotide exchange factor II (CalDAG-GEFII) or Ras guanyl-releasing protein, activates the Erk/MAP kinase cascade and regulates T-cell/B-cell development, homeostasis and differentiation by coupling T-lymphocyte/B-lymphocyte antigen receptors to Ras. RASGRP1 also regulates NK cell cytotoxicity and ITAM-dependent cytokine production by activation of Ras-mediated ERK and JNK pathways. RASGRP2, also called calcium and DAG-regulated guanine nucleotide exchange factor I (CalDAG-GEFI), Cdc25-like protein (CDC25L), or F25B3.3 kinase-like protein, specifically activates Rap and may also activate other GTPases such as RRAS, RRAS2, NRAS, KRAS but not HRAS. RASGRP2 is involved in aggregation of platelets and adhesion of T-lymphocytes and neutrophils probably through inside-out integrin activation, as well as in the muscarinic acetylcholine receptor M1/CHRM1 signaling pathway. RASGRP3, also called calcium and DAG-regulated guanine nucleotide exchange factor III (CalDAG-GEFIII), or guanine nucleotide exchange factor for Rap1, is a guanine nucleotide-exchange factor activating H-Ras, R-Ras and Ras-associated protein-1/2. It functions as an important mediator of signaling downstream from receptor coupled phosphoinositide turnover in B and T cells. RASGRP4 may function in mast cell differentiation. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 568967547  88 PHKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYVEMQ 137
Cdd:cd20808    1 KHNFQETTYFKPTFCDHCTGLLWGLIKQGYKCKDCGINCHKHCKDLVVVE 50

Src homology 3 domain of Yes Protein Tyrosine Kinase; Yes (or c-Yes) is a member of the Src subfamily of proteins, which are cytoplasmic (or non-receptor) PTKs. c-Yes kinase is the cellular homolog of the oncogenic protein (v-Yes) encoded by the Yamaguchi 73 and Esh sarcoma viruses. It displays functional overlap with other Src subfamily members, particularly Src. It also shows some unique functions such as binding to occludins, transmembrane proteins that regulate extracellular interactions in tight junctions. Yes also associates with a number of proteins in different cell types that Src does not interact with, like JAK2 and gp130 in pre-adipocytes, and Pyk2 in treated pulmonary vein endothelial cells. Although the biological function of Yes remains unclear, it appears to have a role in regulating cell-cell interactions and vesicle trafficking in polarized cells. Src kinases contain an N-terminal SH4 domain with a myristoylation site, followed by SH3 and SH2 domains, a tyr kinase domain, and a regulatory C-terminal region containing a conserved tyr. They are activated by autophosphorylation at the tyr kinase domain, but are negatively regulated by phosphorylation at the C-terminal tyr by Csk (C-terminal Src Kinase). The SH3 domain of Src kinases contributes to substrate recruitment by binding adaptor proteins/substrates, and regulation of kinase activity through an intramolecular interaction. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....
gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVIDDSNEEWW--RGKIGEKVGFFPPNFII 298
Cdd:cd12007    2 IFVALYDYEARTTEDLSFKKGERFQIINNTEGDWWeaRSIATGKNGYIPSNYVA 55

Src Homology 3 domain of Bbc1 and similar domains; This subfamily is composed of Saccharomyces cerevisiae Bbc1p, also called Mti1p (Myosin tail region-interacting protein), and similar proteins. Bbc1p interacts with and regulates type I myosins in yeast, Myo3p and Myo5p, which are involved in actin cytoskeletal reorganization. It also binds and inhibits Las17, a WASp family protein that functions as an activator of the Arp2/3 complex. Bbc1p contains an N-terminal SH3 domain. SH3 domains bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs; they play a role in the regulation of enzymes by intramolecular interactions, changing the subcellular localization of signal pathway components and mediate multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....
gi 568967547 249 VALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKI-----GEKVGFFPPNFI 297
Cdd:cd11887    5 KALYPYESDHEDDLNFDVGQLITVTEEEDADWYFGEYvdsngNTKEGIFPKNFV 58

Src Homology 3 domain of Mixed Lineage Kinases; MLKs are Serine/Threonine Kinases (STKs), catalyzing the transfer of the gamma-phosphoryl group from ATP to S/T residues on protein substrates. MLKs act as mitogen-activated protein kinase kinase kinases (MAP3Ks, MKKKs, MAPKKKs), which phosphorylate and activate MAPK kinases (MAPKKs or MKKs or MAP2Ks), which in turn phosphorylate and activate MAPKs during signaling cascades that are important in mediating cellular responses to extracellular signals. MLKs play roles in immunity and inflammation, as well as in cell death, proliferation, and cell cycle regulation. Mammals have four MLKs (MLK1-4), mostly conserved in vertebrates, which contain an SH3 domain, a catalytic kinase domain, a leucine zipper, a proline-rich region, and a CRIB domain that mediates binding to GTP-bound Cdc42 and Rac. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....
gi 568967547 249 VALYRFKALEKDDLDFPPGEKITVID-----DSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11876    3 TALFDYDARGEDELTLRRGQPVEVLSkdaavSGDEGWWTGKIGDKVGIFPSNYV 56

Src homology 3 domain of Fyn and Yrk Protein Tyrosine Kinases; Fyn and Yrk (Yes-related kinase) are members of the Src subfamily of proteins, which are cytoplasmic (or non-receptor) PTKs. Fyn, together with Lck, plays a critical role in T-cell signal transduction by phosphorylating ITAM (immunoreceptor tyr activation motif) sequences on T-cell receptors, ultimately leading to the proliferation and differentiation of T-cells. In addition, Fyn is involved in the myelination of neurons, and is implicated in Alzheimer's and Parkinson's diseases. Yrk has been detected only in chickens. It is primarily found in neuronal and epithelial cells and in macrophages. It may play a role in inflammation and in response to injury. Src kinases contain an N-terminal SH4 domain with a myristoylation site, followed by SH3 and SH2 domains, a tyr kinase domain, and a regulatory C-terminal region containing a conserved tyr. They are activated by autophosphorylation at the tyr kinase domain, but are negatively regulated by phosphorylation at the C-terminal tyr by Csk (C-terminal Src Kinase). The SH3 domain of Src kinases contributes to substrate recruitment by binding adaptor proteins/substrates, and regulation of kinase activity through an intramolecular interaction. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 568967547 248 FVALYRFKALEKDDLDFPPGEKITVIDDSNEEWW--RGKIGEKVGFFPPNFI 297
Cdd:cd12006    3 FVALYDYEARTEDDLSFHKGEKFQILNSSEGDWWeaRSLTTGETGYIPSNYV 54

protein kinase C conserved region 1 (C1 domain) found in the 190 kDa guanine nucleotide exchange factor (p190RhoGEF)-like family; The p190RhoGEF-like protein family includes p190RhoGEF, Rho guanine nucleotide exchange factor 2 (ARHGEF2), A-kinase anchor protein 13 (AKAP-13) and similar proteins. p190RhoGEF is a brain-enriched, RhoA-specific guanine nucleotide exchange factor that regulates signaling pathways downstream of integrins and growth factor receptors. It is involved in axonal branching, synapse formation and dendritic morphogenesis, as well as in focal adhesion formation, cell motility and B-lymphocytes activation. ARHGEF2 acts as a guanine nucleotide exchange factor (GEF) that activates Rho-GTPases by promoting the exchange of GDP for GTP. It is thought to play a role in actin cytoskeleton reorganization in different tissues since its activation induces formation of actin stress fibers. AKAP-13 is a scaffold protein that plays an important role in assembling signaling complexes downstream of several types of G protein-coupled receptors. It activates RhoA in response to signaling via G protein-coupled receptors via its function as Rho guanine nucleotide exchange factor. It may also activate other Rho family members. AKAP-13 plays a role in cell growth, cell development and actin fiber formation. Members of this family share a common domain architecture containing C1, RhoGEF or Dbl-homologous (DH), and Pleckstrin Homology (PH) domains. Some members may contain additional domains such as the DUF5401 domain. This model describes the C1 domain. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

                         10        20        30
                 ....*....|....*....|....*....|....*
gi 568967547 102 CDVCARmiVLNNKFGLRCKNCKTNIHEH-CQSYVE 135
Cdd:cd20815   17 CDVCSK--PLTNKPALQCENCSVNVHDSsCKDQLA 49

Second Src Homology 3 domain of Nck adaptor proteins; Nck adaptor proteins regulate actin cytoskeleton dynamics by linking proline-rich effector molecules to protein tyrosine kinases and phosphorylated signaling intermediates. They contain three SH3 domains and a C-terminal SH2 domain. They function downstream of the PDGFbeta receptor and are involved in Rho GTPase signaling and actin dynamics. Vertebrates contain two Nck adaptor proteins: Nck1 (also called Nckalpha) and Nck2 (also called Nckbeta or Growth factor receptor-bound protein 4, Grb4), which show partly overlapping functions but also bind distinct targets. Their SH3 domains are involved in recruiting downstream effector molecules, such as the N-WASP/Arp2/3 complex, which when activated induces actin polymerization that results in the production of pedestals, or protrusions of the plasma membrane. The second SH3 domain of Nck appears to prefer ligands containing the APxxPxR motif. SH3 domains are protein interaction domains that usually bind to proline-rich ligands with moderate affinity and selectivity, preferentially a PxxP motif. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 568967547 248 FVALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11766    2 AVVKFNYEAQREDELSLRKGDRVLVLEKSSDGWWRGECNGQVGWFPSNYV 51

Src homology 3 domain of Cortactin and related proteins; This subfamily includes cortactin, Abp1 (actin-binding protein 1), hematopoietic lineage cell-specific protein 1 (HS1), and similar proteins. These proteins are involved in regulating actin dynamics through direct or indirect interaction with the Arp2/3 complex, which is required to initiate actin polymerization. They all contain at least one C-terminal SH3 domain. Cortactin and HS1 bind Arp2/3 and actin through an N-terminal region that contains an acidic domain and several copies of a repeat domain found in cortactin and HS1. Abp1 binds actin via an N-terminal actin-depolymerizing factor (ADF) homology domain. Yeast Abp1 binds Arp2/3 directly through two acidic domains. Mammalian Abp1 does not directly interact with Arp2/3; instead, it regulates actin dynamics indirectly by interacting with dynamin and WASP family proteins. The C-terminal region of these proteins acts as an adaptor or scaffold that can connect membrane trafficking and signaling proteins that bind the SH3 domain within the actin network. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 568967547 249 VALYRFKALEKDDLDFPPGEKITVIDDSNEEWWRGKI-GEKVGFFPPNFI 297
Cdd:cd11819    3 KALYDYQAAEDNEISFVEGDIITQIEQIDEGWWLGVNaKGQKGLFPANYV 52

Src homology 3 domain of Apoptosis Stimulating of p53 proteins (ASPP); The ASPP family of proteins bind to important regulators of apoptosis (p53, Bcl-2, and RelA) and cell growth (APCL, PP1). They share similarity at their C-termini, where they harbor a proline-rich region, four ankyrin (ANK) repeats, and an SH3 domain. Vertebrates contain three members of the family: ASPP1, ASPP2, and iASPP. ASPP1 and ASPP2 activate the apoptotic function of the p53 family of tumor suppressors (p53, p63, and p73), while iASPP is an oncoprotein that specifically inhibits p53-induced apoptosis. The expression of ASPP proteins is altered in tumors; ASPP1 and ASPP2 are downregulated whereas iASPP is upregulated is some cancer types. ASPP proteins also bind and regulate protein phosphatase 1 (PP1), and this binding is competitive with p53 binding. The SH3 domain and the ANK repeats of ASPP contribute to the p53 binding site; they bind to the DNA binding domain of p53. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 568967547 250 ALYRFKALEKDDLDFPPGEKITVI---DDSNEEWWRGKIGEKVGFFPPNFI 297
Cdd:cd11807    5 ALFDYEAENGDELSFREGDELTVLrkgDDDETEWWWARLNDKEGYVPRNLL 55

second protein kinase C conserved region 1 (C1 domain) found in protein kinase D3 (PKD3) and similar proteins; PKD3 is also called PRKD3, PRKCN, serine/threonine-protein kinase D3 (nPKC-D3), protein kinase C nu type (nPKC-nu), or protein kinase EPK2. It converts transient diacylglycerol (DAG) signals into prolonged physiological effects, downstream of PKC. It is involved in the regulation of the cell cycle by modulating microtubule nucleation and dynamics. PKD3 acts as a key mediator in several cancer development signaling pathways. PKD3 contains N-terminal tandem cysteine-rich zinc binding C1 (PKC conserved region 1), central PH (Pleckstrin Homology), and C-terminal catalytic kinase domains. This model corresponds to the second C1 domain. The C1 domain is a cysteine-rich zinc binding domain that does not bind DNA nor possess structural similarity to conventional zinc finger domains; it contains two separate Zn(2+)-binding sites.

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gi 568967547  88 PHKFKDHFFKKPKFCDVCARMIVLNNKFGLRCKNCKTNIHEHCQSYVEmQRCFGKI 143
Cdd:cd20844    5 PHTFAVHSYTRPTICQYCKRLLKGLFRQGMQCKDCRFNCHKRCASKVP-RDCLGEV 59

Src Homology 3 domain of Mixed Lineage Kinases 1, 2, and 3; MLKs 1, 2, and 3 are Serine/Threonine Kinases (STKs), catalyzing the transfer of the gamma-phosphoryl group from ATP to S/T residues on protein substrates. MLKs act as mitogen-activated protein kinase kinase kinases (MAP3Ks, MKKKs, MAPKKKs), which phosphorylate and activate MAPK kinases (MAPKKs or MKKs or MAP2Ks), which in turn phosphorylate and activate MAPKs during signaling cascades that are important in mediating cellular responses to extracellular signals. MLKs play roles in immunity and inflammation, as well as in cell death, proliferation, and cell cycle regulation. Little is known about the specific function of MLK1, also called MAP3K9. It is capable of activating the c-Jun N-terminal kinase pathway. Mice lacking both MLK1 and MLK2 are viable, fertile, and have normal life spans. MLK2, also called MAP3K10, is abundant in brain, skeletal muscle, and testis. It functions upstream of the MAPK, c-Jun N-terminal kinase. It binds hippocalcin, a calcium-sensor protein that protects neurons against calcium-induced cell death. Both MLK2 and hippocalcin may be associated with the pathogenesis of Parkinson's disease. MLK3, also called MAP3K11, is highly expressed in breast cancer cells and its signaling through c-Jun N-terminal kinase has been implicated in the migration, invasion, and malignancy of cancer cells. It also functions as a negative regulator of Inhibitor of Nuclear Factor-KappaB Kinase (IKK) and thus, impacts inflammation and immunity. MLKs contain an SH3 domain, a catalytic kinase domain, a leucine zipper, a proline-rich region, and a CRIB domain that mediates binding to GTP-bound Cdc42 and Rac. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 568967547 247 YFVALYRFKALEKDDLDFPPGEKITVID-DS----NEEWWRGKIGEKVGFFPPNFIIR 299
Cdd:cd12059    1 VWTAVFDYEASAEDELTLRRGDRVEVLSkDSavsgDEGWWTGKINDRVGIFPSNYVTS 58