The PB1 domain is present in the p51 protein, a homolog of the p67 protein. p51 plays an important role in NADPH oxidase activation during phagosytosis. The PB1 domain is a modular domain mediating specific protein-protein interaction in many critical cell processes such as osteoclastogenesis, angiogenesis, early cardiovascular development, and cell polarity. A canonical PB1-PB1 interaction, which involves heterodimerization of two PB1 domains, is required for the formation of macromolecular signaling complexes ensuring specificity and fidelity during cellular signaling. The interaction between two PB1 domain depends on the type of PB1. There are three types of PB1 domains: type I which contains an OPCA motif, acidic aminoacid cluster, type II which contains a basic cluster, and type I/II which contains both an OPCA motif and a basic cluster. Interactions of PB1 domains with other protein domains have been described as noncanonical PB1-interactions. The PB1 domain module is conserved in amoebas, fungi, animals, and plants.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 767956103 280 VTVQCAFTVALRARRGADLSSLRALLGQALPHQAQLGQLSYLAPGEDGHWVPIPEEESLQRAWQDAAACPRGLQLQCR 357
Cdd:cd06411    1 VTVQCAFTVALRAPRGADVSSLRALLSQALPQQAQRGQLSYRAPGEDGHWVPISGEESLQRAWQDVADGPRGLQLQCR 78

Tetratricopeptide (TPR) repeat [General function prediction only];

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103  38 ARLCFNAGCVHLLAGDPEAALRAFDQAVTKDTCMAVGFFQRGVANFQLARFQEALSDFWLALEQLRGHA----------- 106
Cdd:COG0457    8 AEAYNNLGLAYRRLGRYEEAIEDYEKALELDPDDAEALYNLGLAYLRLGRYEEALADYEQALELDPDDAealnnlglalq 87

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 767956103 107 -------AIDYTQLGLRFKLQAWEVLHNVASAQCQLGLWTEAASSLREAMSKWPEG--SLNGLDSALDQVQVVASAIPD 176
Cdd:COG0457   88 algryeeALEDYDKALELDPDDAEALYNLGLALLELGRYDEAIEAYERALELDPDDadALYNLGIALEKLGRYEEALEL 166

The PB1 domain is present in the p51 protein, a homolog of the p67 protein. p51 plays an important role in NADPH oxidase activation during phagosytosis. The PB1 domain is a modular domain mediating specific protein-protein interaction in many critical cell processes such as osteoclastogenesis, angiogenesis, early cardiovascular development, and cell polarity. A canonical PB1-PB1 interaction, which involves heterodimerization of two PB1 domains, is required for the formation of macromolecular signaling complexes ensuring specificity and fidelity during cellular signaling. The interaction between two PB1 domain depends on the type of PB1. There are three types of PB1 domains: type I which contains an OPCA motif, acidic aminoacid cluster, type II which contains a basic cluster, and type I/II which contains both an OPCA motif and a basic cluster. Interactions of PB1 domains with other protein domains have been described as noncanonical PB1-interactions. The PB1 domain module is conserved in amoebas, fungi, animals, and plants.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 767956103 280 VTVQCAFTVALRARRGADLSSLRALLGQALPHQAQLGQLSYLAPGEDGHWVPIPEEESLQRAWQDAAACPRGLQLQCR 357
Cdd:cd06411    1 VTVQCAFTVALRAPRGADVSSLRALLSQALPQQAQRGQLSYRAPGEDGHWVPISGEESLQRAWQDVADGPRGLQLQCR 78

PB1 domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103  279 TVTVQCAF----TVALRARRGADLSSLRALLGQALPHQAQLGQLSYlaPGEDGHWVPIPEEESLQRAWQDAAACP-RGLQ 353
Cdd:pfam00564   1 TVRLKLRYgggiRRFLSVSRGISFEELRALVEQRFGLDDVDFKLKY--PDEDGDLVSLTSDEDLEEALEEARSLGsKSLR 78

                  ....*.
gi 767956103  354 LQCRGA 359
Cdd:pfam00564  79 LHVFPT 84

PB1 domain; Phox and Bem1p domain, present in many eukaryotic cytoplasmic signalling proteins. The domain adopts a beta-grasp fold, similar to that found in ubiquitin and Ras-binding domains. A motif, variously termed OPR, PC and AID, represents the most conserved region of the majority of PB1 domains, and is necessary for PB1 domain function. This function is the formation of PB1 domain heterodimers, although not all PB1 domain pairs associate.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103   279 TVTVQCAF---TVALRARRGADLSSLRALLGQALPHQAQLGQLSYLapGEDGHWVPIPEEESLQRAWQDAA-ACPRGLQL 354
Cdd:smart00666   1 TVDVKLRYggeTRRLSVPRDISFEDLRSKVAKRFGLDNQSFTLKYQ--DEDGDLVSLTSDEDLEEAIEEYDsLGSKKLRL 78

                   ..
gi 767956103   355 QC 356
Cdd:smart00666  79 HV 80

The PB1 domain is present in the p51 protein, a homolog of the p67 protein. p51 plays an important role in NADPH oxidase activation during phagosytosis. The PB1 domain is a modular domain mediating specific protein-protein interaction in many critical cell processes such as osteoclastogenesis, angiogenesis, early cardiovascular development, and cell polarity. A canonical PB1-PB1 interaction, which involves heterodimerization of two PB1 domains, is required for the formation of macromolecular signaling complexes ensuring specificity and fidelity during cellular signaling. The interaction between two PB1 domain depends on the type of PB1. There are three types of PB1 domains: type I which contains an OPCA motif, acidic aminoacid cluster, type II which contains a basic cluster, and type I/II which contains both an OPCA motif and a basic cluster. Interactions of PB1 domains with other protein domains have been described as noncanonical PB1-interactions. The PB1 domain module is conserved in amoebas, fungi, animals, and plants.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 767956103 280 VTVQCAFTVALRARRGADLSSLRALLGQALPHQAQLGQLSYLAPGEDGHWVPIPEEESLQRAWQDAAACPRGLQLQCR 357
Cdd:cd06411    1 VTVQCAFTVALRAPRGADVSSLRALLSQALPQQAQRGQLSYRAPGEDGHWVPISGEESLQRAWQDVADGPRGLQLQCR 78

C-terminal Src Homology 3 domain of the p67phox subunit of NADPH oxidase and similar proteins; This subfamily is composed of p67phox, NADPH oxidase activator 1 (Noxa1), and similar proteins. p67phox, also called Neutrophil cytosol factor 2 (NCF-2), and Noxa1 are homologs and are the cytosolic subunits of the phagocytic (Nox2) and nonphagocytic (Nox1) NADPH oxidase complexes, respectively. NADPH oxidase catalyzes the transfer of electrons from NADPH to oxygen during phagocytosis forming superoxide and reactive oxygen species. p67phox and Noxa1 play regulatory roles. p67phox contains N-terminal TPR, first SH3 (or N-terminal or central SH3), PB1, and C-terminal SH3 domains. Noxa1 has a similar domain architecture except it is lacking the N-terminal SH3 domain. The TPR domain of both binds activated GTP-bound Rac, while the C-terminal SH3 domain of p67phox and Noxa1 binds the polyproline motif found at the C-terminus of p47phox and Noxo1, respectively. 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        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLCEepdvplaVDQAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd11870    1 QVVALHRYEAQGPEDLGFREGDTIDVLSE-------VNEAWLEGHSDGRVGIFPKCFVVP 53

PB1 domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103  279 TVTVQCAF----TVALRARRGADLSSLRALLGQALPHQAQLGQLSYlaPGEDGHWVPIPEEESLQRAWQDAAACP-RGLQ 353
Cdd:pfam00564   1 TVRLKLRYgggiRRFLSVSRGISFEELRALVEQRFGLDDVDFKLKY--PDEDGDLVSLTSDEDLEEALEEARSLGsKSLR 78

                  ....*.
gi 767956103  354 LQCRGA 359
Cdd:pfam00564  79 LHVFPT 84

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 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLCEEPDvplavdqAWLEGHC-DGRIGIFPKCF 423
Cdd:cd00174    1 YARALYDYEAQDDDELSFKKGDIITVLEKDDD-------GWWEGELnGGREGLFPANY 51

Third Src Homology 3 domain (SH3C) of CD2-associated protein and similar proteins; This subfamily is composed of the third SH3 domain (SH3C) 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. SH3C of both proteins have been shown to bind to 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        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 767956103 374 YSAQGPEDLGFRQGDTVDVLCEEpdvplAVDQAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd11875    8 YEAENEDELTLREGDIVTILSKD-----CEDKGWWKGELNGKRGVFPDNFVEP 55

Third N-terminal Src homology 3 domain of Dynamin Binding Protein, also called Tuba; DNMBP or Tuba is a cdc42-specific guanine nucleotide exchange factor (GEF) that contains four N-terminal SH3 domains, a central RhoGEF [or Dbl homology (DH)] domain followed by a Bin/Amphiphysin/Rvs (BAR) domain, and two C-terminal SH3 domains. It provides a functional link between dynamin and key regulatory proteins of the actin cytoskeleton. It plays an important role in regulating cell junction configuration. The four N-terminal SH3 domains of DNMBP binds the GTPase dynamin, which plays an important role in the fission of endocytic vesicles. 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 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLcEEPDvplavdQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11796    1 QARVLQDLSAQLDEELDLREGDVVTIT-GILD------KGWFRGELNGRRGIFPEGFV 51

Tetratricopeptide (TPR) repeat [General function prediction only];

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103  38 ARLCFNAGCVHLLAGDPEAALRAFDQAVTKDTCMAVGFFQRGVANFQLARFQEALSDFWLALEQLRGHA----------- 106
Cdd:COG0457    8 AEAYNNLGLAYRRLGRYEEAIEDYEKALELDPDDAEALYNLGLAYLRLGRYEEALADYEQALELDPDDAealnnlglalq 87

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 767956103 107 -------AIDYTQLGLRFKLQAWEVLHNVASAQCQLGLWTEAASSLREAMSKWPEG--SLNGLDSALDQVQVVASAIPD 176
Cdd:COG0457   88 algryeeALEDYDKALELDPDDAEALYNLGLALLELGRYDEAIEAYERALELDPDDadALYNLGIALEKLGRYEEALEL 166

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        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLceepDvplAVDQAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd11805    1 RVQALYDFNPQEPGELEFRRGDIITVL----D---SSDPDWWKGELRGRVGIFPANYVQP 53

Src Homology 3 domain of SH3 domain-containing protein 21 (SH3D21) and similar proteins; N-terminal SH3 domain of the uncharacterized protein SH3 domain-containing protein 21, and similar uncharacterized domains, it belongs to the CD2AP-like_3 subfamily of proteins. The CD2AP-like_3 subfamily is composed of the third SH3 domain (SH3C) 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. SH3C of both proteins have been shown to bind to 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        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 767956103 374 YSAQGPEDLGFRQGDTVDVLCEEPDvplavDQAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd12142    8 YNPVAPDELALKKGDVIEVISKETE-----DEGWWEGELNGRRGFFPDNFVMP 55

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        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLCEEpdvplavDQAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd11840    1 QVIALFPYTAQNEDELSFQKGDIINVLSKD-------DPDWWRGELNGQTGLFPSNYVEP 53

Lipoprotein NlpI, contains TPR repeats [Cell wall/membrane/envelope biogenesis];

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103  20 RGDWARALHLFSGvpAPPARLcfNAGCVHLLAGDPEAALRAFDQAVTKDTCMAVGFFQRGVANFQLARFQEALSDFWLAL 99
Cdd:COG4785   93 IADFDQALELDPD--LAEAYN--NRGLAYLLLGDYDAALEDFDRALELDPDYAYAYLNRGIALYYLGRYELAIADLEKAL 168

                 .
gi 767956103 100 E 100
Cdd:COG4785  169 E 169

Src homology 3 domain of Endophilin-A; Endophilins play roles in synaptic vesicle formation, virus budding, mitochondrial morphology maintenance, receptor-mediated endocytosis inhibition, and endosomal sorting. They are classified into two types, A and B. Vertebrates contain three endophilin-A isoforms (A1, A2, and A3). Endophilin-A proteins are enriched in the brain and play multiple roles in receptor-mediated endocytosis. They tubulate membranes and regulate calcium influx into neurons to trigger the activation of the endocytic machinery. They are also involved in the sorting of plasma membrane proteins, actin filament assembly, and the uncoating of clathrin-coated vesicles for fusion with endosomes. Endophilins contain an N-terminal N-BAR domain (BAR domain with an additional N-terminal amphipathic helix), followed by a variable region containing proline clusters, and a C-terminal SH3 domain. 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 767956103 370 AQHSYSAQGPEDLGFRQGDTVDVLCEepdvplaVDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11803    5 ALYDFEPENEGELGFKEGDIITLTNQ-------IDENWYEGMVNGQSGFFPVNYV 52

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        50
                 ....*....|....*....|....*....|....*....|....*....|....*.
gi 767956103 368 VVAQHSYSAQGPEDLGFRQGDTVDVLCEepdvplaVDQAWLEGHCDGRIGIFPKCF 423
Cdd:cd11817    2 AVALYDFTGETEEDLSFQRGDRILVTEH-------LDAEWSRGRLNGREGIFPRAF 50

Src Homology 3 domain of Mixed Lineage Kinase 4; MLK4 is a Serine/Threonine Kinase (STK), 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. The specific function of MLK4 is yet to be determined. Mutations in the kinase domain of MLK4 have been detected in colorectal cancers. MLK4 contains 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 767956103 370 AQHSYSAQGPEDLGFRQGDTVDVLCEepDVPLAVDQAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd12058    4 ALYDYEASGEDELSLRRGDVVEVLSQ--DAAVSGDDGWWAGKIRHRLGIFPANYVTR 58

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.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 767956103 374 YSAQGPEDLGFRQGDTVDVLCEepDVPLAVDQAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd12059    8 YEASAEDELTLRRGDRVEVLSK--DSAVSGDEGWWTGKINDRVGIFPSNYVTS 58

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 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLcEEPDvplaVDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11842    1 KAVALYDFAGEQPGDLAFQKGDIITIL-KKSD----SQNDWWTGRIGGREGIFPANYV 53

Tetratricopeptide (TPR) repeat [General function prediction only];

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103   6 DLVRAWH-LGAQAVDRGDWARALHLFS-GVPAPP--ARLCFNAGCVHLLAGDPEAALRAFDQAVTKDTCMAVGFFQRGVA 81
Cdd:COG0457   74 DDAEALNnLGLALQALGRYEEALEDYDkALELDPddAEALYNLGLALLELGRYDEAIEAYERALELDPDDADALYNLGIA 153

                         90       100       110       120       130       140
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 767956103  82 NFQLARFQEALSDFWLALEQLRGHAAIDYTQLGLRFKLQAWEVLHNVASAQCQLGLWTEAASSLREA 148
Cdd:COG0457  154 LEKLGRYEEALELLEKLEAAALAALLAAALGEAALALAAAEVLLALLLALEQALRKKLAILTLAALA 220

The PB1 domain is a modular domain mediating specific protein-protein interactions which play a role in many critical cell processes, such as osteoclastogenesis, angiogenesis, early cardiovascular development, and cell polarity. A canonical PB1-PB1 interaction, which involves heterodimerization of two PB1 domain, is required for the formation of macromolecular signaling complexes ensuring specificity and fidelity during cellular signaling. The interaction between two PB1 domain depends on the type of PB1. There are three types of PB1 domains: type I which contains an OPCA motif, acidic aminoacid cluster, type II which contains a basic cluster, and type I/II which contains both an OPCA motif and a basic cluster. Interactions of PB1 domains with other protein domains have been described as a noncanonical PB1-interactions. The PB1 domain module is conserved in amoebas, fungi, animals, and plants.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 767956103 293 RRGADLSSLRALLGQALPHQAQLGQLSYlaPGEDGHWVPIPEEESLQRAWQDAAACPRG-LQLQCR 357
Cdd:cd05992   18 SRSISFEDLRSKIAEKFGLDAVSFKLKY--PDEDGDLVTISSDEDLEEAIEEARRSGSKkLRLFVF 81

Predicted O-linked N-acetylglucosamine transferase, SPINDLY family [Posttranslational modification, protein turnover, chaperones];

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103  15 AQAVDRGDWARALHLFSGVPAPPARLCFNAGCVHLLAGDPEAALRAFDQAVTKDTCMAVGFFQRGVANFQLARFQEALSD 94
Cdd:COG3914   55 AAAALLALAAGEAAAAAAALLLLAALLELAALLLQALGRYEEALALYRRALALNPDNAEALFNLGNLLLALGRLEEALAA 134

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 767956103  95 FWLALE------------------QLRGHAAIDYTQLGLRFKLQAWEVLHNVASAQCQLGLWTEAASSLREAMSKWPE 154
Cdd:COG3914  135 LRRALAlnpdfaeaylnlgealrrLGRLEEAIAALRRALELDPDNAEALNNLGNALQDLGRLEEAIAAYRRALELDPD 212

Second Src Homology 3 domain of FCH and double SH3 domains protein 1; FCHSD1 has a domain structure consisting of an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs), two SH3, and C-terminal proline-rich domains. It has only been characterized in silico and its function is unknown. 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 767956103 368 VVAQHSYSAQGPEDLGFRQGDTVDVLCEEPDvplAVDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11895    2 ARALYSYTGQSPEELSFPEGALIRLLPRAQD---GVDDGFWRGEFGGRVGVFPSLLV 55

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        50
                 ....*....|....*....|....*....|....*....|....*....|....*
gi 767956103 370 AQHSYSAQGPEDLGFRQGDTVDVLCEepdvplaVDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11874    4 VLFSYTPQNEDELELKVGDTIEVLGE-------VEEGWWEGKLNGKVGVFPSNFV 51

Src Homology 3 domain of Myosin XV; This subfamily is composed of proteins with similarity to Myosin XVa. Myosin XVa is an unconventional myosin that is critical for the normal growth of mechanosensory stereocilia of inner ear hair cells. Mutations in the myosin XVa gene are associated with nonsyndromic hearing loss. Myosin XVa contains a unique N-terminal extension followed by a motor domain, light chain-binding IQ motifs, and a tail consisting of a pair of MyTH4-FERM tandems separated by a SH3 domain, and a PDZ 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 767956103 368 VVAQHSYSAQGPEDLGFRQGDTVDVLCEEPDVplavDQAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd11884    2 VVAVRAYITRDQTLLSFHKGDVIKLLPKEGPL----DPGWLFGTLDGRSGAFPKEYVQP 56

First Src Homology 3 domain (SH3A) of CD2-associated protein and similar proteins; This subfamily is composed of the first SH3 domain (SH3A) 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. SH3A of both proteins bind to an atypical PXXXPR motif at the C-terminus of Cbl and the cytoplasmic domain of the cell adhesion protein CD2. CIN85 SH3A binds to internal proline-rich motifs within the proline-rich region; this intramolecular interaction serves as a regulatory mechanism to keep CIN85 in a closed conformation, preventing the recruitment of other proteins. CIN85 SH3A has also been shown to bind 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        50
                 ....*....|....*....|....*....|....*....|....*....|....*...
gi 767956103 368 VVAQHSYSAQGPEDLGFRQGDTV-DVLceepdvplAVDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11873    2 VIVEFDYDAEEPDELTLKVGDIItNVK--------KMEEGWWEGTLNGKRGMFPDNFV 51

Second Src Homology 3 domain (SH3B) of Cbl-interacting protein of 85 kDa; CIN85, also called SH3 domain-containing kinase-binding protein 1 (SH3KBP1) or CD2-binding protein 3 (CD2BP3) or Ruk, is an adaptor protein that is involved in the downregulation of receptor tyrosine kinases by facilitating endocytosis through interaction with endophilin-associated ubiquitin ligase Cbl proteins. It is also important in many other cellular processes including vesicle-mediated transport, cytoskeletal remodelling, apoptosis, cell adhesion and migration, and viral infection, among others. CIN85 exists as multiple variants from alternative splicing; the main variant contains three SH3 domains, a proline-rich region, and a C-terminal coiled-coil domain. All of these domains enable CIN85 to bind various protein partners and assemble complexes that have been implicated in many different functions. This alignment model represents the second SH3 domain (SH3B) of CIN85. SH3B has been shown to bind Cbl proline-rich peptides and 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        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 767956103 373 SYSAQGPEDLGFRQGDTVDVLCEepdvplaVDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd12055    7 SYLPQNEDELELKVGDIIEVVGE-------VEEGWWEGVLNGKTGMFPSNFI 51

First Src Homology 3 domain of Vinexin, also called Sorbin and SH3 domain containing 3 (Sorbs3); Vinexin is also called Sorbs3, SH3P3, and SH3-containing adapter molecule 1 (SCAM-1). It is an adaptor protein containing one sorbin homology (SoHo) and three SH3 domains. Vinexin was first identified as a vinculin binding protein; it is co-localized with vinculin at cell-ECM and cell-cell adhesion sites. There are several splice variants of vinexin: alpha, which contains the SoHo and three SH3 domains and displays tissue-specific expression; and beta, which contains only the three SH3 domains and is widely expressed. Vinexin alpha stimulates the accumulation of F-actin at focal contact sites. Vinexin also promotes keratinocyte migration and wound healing. The SH3 domains of vinexin have been reported to bind a number of ligands including vinculin, WAVE2, DLG5, Abl, and Cbl. 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 767956103 370 AQHSYSAQGPEDLGFRQGDTVDVLCEepdvplaVDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11921    5 LKFDFQAQSPKELTLQKGDIVYIHKE-------VDKNWLEGEHHGRVGIFPANYV 52

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        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLCEEPDvplavdqAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd11766    1 PAVVKFNYEAQREDELSLRKGDRVLVLEKSSD-------GWWRGECNGQVGWFPSNYVTE 53

Src homology 3 domain of Abl Interactor proteins; Abl interactor (Abi) proteins are adaptor proteins serving as binding partners and substrates of Abl tyrosine kinases. They are involved in regulating actin cytoskeletal reorganization and play important roles in membrane-ruffling, endocytosis, cell motility, and cell migration. They localize to sites of actin polymerization in epithelial adherens junction and immune synapses, as well as to the leading edge of lamellipodia. Vertebrates contain two Abi proteins, Abi1 and Abi2. Abi1 displays a wide expression pattern while Abi2 is highly expressed in the eye and brain. Abi proteins contain a homeobox homology domain, a proline-rich region, and a SH3 domain. The SH3 domain of Abi binds to a PxxP motif in Abl. 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 767956103 368 VVAQHSYSAQGPEDLGFRQGDTVDVLCEEPDvplavdqAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11826    2 VVALYDYTADKDDELSFQEGDIIYVTKKNDD-------GWYEGVLNGVTGLFPGNYV 51

C-terminal Src homology 3 domain of GRB2-related adaptor protein 2; GRAP2 is also called GADS (GRB2-related adapter downstream of Shc), GrpL, GRB2L, Mona, or GRID (Grb2-related protein with insert domain). It is expressed specifically in the hematopoietic system. It 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. It also has roles in antigen-receptor and tyrosine kinase mediated signaling. GRAP2 is unique from other GRB2-like adaptor proteins in that it can be regulated by caspase cleavage. It contains an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. The C-terminal SH3 domain of GRAP2 binds to different motifs found in substrate peptides including the typical PxxP motif in hematopoietic progenitor kinase 1 (HPK1), the RxxK motif in SLP-76 and HPK1, and the RxxxxK motif in phosphatase-like protein HD-PTP. 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        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVL-CEEPdvplavdqAWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd11950    1 QVRALYDFEALEDDELGFNSGDVIEVLdSSNP--------SWWKGRLHGKLGLFPANYVAP 53

Src homology 3 domain of ArfGAP with SH3 domain, ankyrin repeat and PH domain containing protein 2; ASAP2 is also called DDEF2 (Development and Differentiation Enhancing Factor 2), AMAP2, centaurin beta-3, or PAG3. It mediates the functions of Arf GTPases vial dual mechanisms: it exhibits GTPase activating protein (GAP) activity towards class I (Arf1) and II (Arf5) Arfs; and it binds class III Arfs (GTP-Arf6) stably without GAP activity. It binds paxillin and is implicated in Fcgamma receptor-mediated phagocytosis in macrophages and in cell migration. ASAP2 contains an N-terminal BAR domain, followed by a Pleckstrin homology (PH) domain, an Arf GAP domain, ankyrin (ANK) repeats, and a C-terminal SH3 domain. 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        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLCEEpdvplavDQAWLEGHCDG---RIGIFPKCFV 424
Cdd:cd11966    1 RVKALYNCVADNPDELTFSEGEIIIVDGEE-------DKEWWIGHIDGeptRRGAFPVSFV 54

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        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLCEEPDvplavdqaWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd11992    1 EYIALYPYSSSEPGDLTFNEGEEILVTQKDGE--------WWTGSIEDRTGIFPSNYVRP 52

Src Homology 3 domain of Class A and B Dedicator of Cytokinesis proteins; DOCK proteins are atypical guanine nucleotide exchange factors (GEFs) that lack the conventional Dbl homology (DH) domain. They are divided into four classes (A-D) based on sequence similarity and domain architecture: class A includes Dock1, 2 and 5; class B includes Dock3 and 4; class C includes Dock6, 7, and 8; and class D includes Dock9, 10 and 11. All DOCKs contain two homology domains: the DHR-1 (Dock homology region-1), also called CZH1 (CED-5, Dock180, and MBC-zizimin homology 1), and DHR-2 (also called CZH2 or Docker). The DHR-1 domain binds phosphatidylinositol-3,4,5-triphosphate while DHR-2 contains the catalytic activity for Rac and/or Cdc42. This subfamily includes only Class A and B DOCKs, which also contain an SH3 domain at the N-terminal region and a PxxP motif at the C-terminus. Class A/B DOCKs are mostly specific GEFs for Rac, except Dock4 which activates the Ras family GTPase Rap1, probably indirectly through interaction with Rap regulatory proteins. The SH3 domain of class A/B DOCKs have been shown to bind Elmo, a scaffold protein that promotes GEF activity of DOCKs by releasing DHR-2 autoinhibition by the intramolecular SH3 domain. 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        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103 369 VAQHSYSAQGPEDLGFRQGDTVDVLCEEPDvplavdqaWLEG---HCDGRIGIFPKCFVV 425
Cdd:cd11872    3 VAIYNFQGDGEHQLSLQVGDTVQILEECEG--------WYRGfslRNKSLKGIFPKSYVH 54

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        50
                 ....*....|....*....|....*....|....*....|....*....|....*.
gi 767956103 369 VAQHSYSAQGPEDLGFRQGDTVdVLCEepdvplAVDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11816    3 VARFDFEGEQEDELSFSEGDVI-TLKE------YVGEEWAKGELNGKIGIFPLNFV 51

Second Src Homology 3 domain of FCH and double SH3 domains protein 2; FCHSD2 has a domain structure consisting of an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs), two SH3, and C-terminal proline-rich domains. It has only been characterized in silico and its function is unknown. 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 767956103 368 VVAQHSYSAQGPEDLGFRQGDTVDVLCEEPDVplavDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11894    2 VKALYDYEGQTDDELSFPEGAIIRILNKENQD----DDGFWEGEFNGRIGVFPSVLV 54

C-terminal (or second) Src homology 3 domain of VAV proteins; VAV proteins function both as cytoplasmic guanine nucleotide exchange factors (GEFs) for Rho GTPases and scaffold proteins and they play important roles in cell signaling by coupling cell surface receptors to various effector functions. They play key roles in processes that require cytoskeletal reorganization including immune synapse formation, phagocytosis, cell spreading, and platelet aggregation, among others. Vertebrates have three VAV proteins (VAV1, VAV2, and VAV3). VAV proteins contain several domains that enable their function: N-terminal calponin homology (CH), acidic, RhoGEF (also called Dbl-homologous or DH), Pleckstrin Homology (PH), C1 (zinc finger), SH2, and two SH3 domains. The SH3 domain of VAV is involved in the localization of proteins to specific sites within the cell, by interacting with proline-rich sequences within target proteins. 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 767956103 369 VAQHSYSAQGPEDLGFRQGDTVDVLCEEPDvplavdQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd11830    3 KARYDFCARDMRELSLKEGDVVKIYNKKGQ------QGWWRGEINGRIGWFPSTYV 52

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        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLCEEPDvplavdqaWLEGHCDGRIGIFPKCFVVP 426
Cdd:cd11991    1 EYVAMYTYESNEQGDLTFQQGDVILVTKKDGD--------WWTGTVGDKTGVFPSNYVRP 52

First Src Homology 3 domain (SH3A) of Cbl-interacting protein of 85 kDa; CIN85, also called SH3 domain-containing kinase-binding protein 1 (SH3KBP1) or CD2-binding protein 3 (CD2BP3) or Ruk, is an adaptor protein that is involved in the downregulation of receptor tyrosine kinases by facilitating endocytosis through interaction with endophilin-associated ubiquitin ligase Cbl proteins. It is also important in many other cellular processes including vesicle-mediated transport, cytoskeletal remodelling, apoptosis, cell adhesion and migration, and viral infection, among others. CIN85 exists as multiple variants from alternative splicing; the main variant contains three SH3 domains, a proline-rich region, and a C-terminal coiled-coil domain. All of these domains enable CIN85 to bind various protein partners and assemble complexes that have been implicated in many different functions. This alignment model represents the first SH3 domain (SH3A) of CIN85; SH3A binds to internal proline-rich motifs within the proline-rich region. This intramolecular interaction serves as a regulatory mechanism to keep CIN85 in a closed conformation, preventing the recruitment of other proteins. SH3A has also been shown to bind ubiquitin and to an atypical PXXXPR motif at the C-terminus of Cbl and the cytoplasmic end of the cell adhesion protein CD2. 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 767956103 367 QVVAQHSYSAQGPEDLGFRQGDTVDVLCEEpdvplavDQAWLEGHCDGRIGIFPKCFV 424
Cdd:cd12052    1 EAIVEFDYKAQHEDELTITVGDIITKIKKD-------DGGWWEGEIKGRRGLFPDNFV 51