Src homology 2 domains; Src homology 2 domains bind phosphotyrosine-containing polypeptides via 2 surface pockets. Specificity is provided via interaction with residues that are distinct from the phosphotyrosine. Only a single occurrence of a SH2 domain has been found in S. cerevisiae.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944   116 WFHGFITRREAERLLQPQPLGCYLVRFSES-AVTFVLSYslvgeemasltqsgpsRSQTCCRHFLLAQLGDGRhVVLGED 194
Cdd:smart00252   3 WYHGFISREEAEKLLKNEGDGDFLVRDSESsPGDYVLSV----------------RVKGKVKHYRIRRNEDGK-FYLEGG 65

                           90
                   ....*....|....*....
gi 568922944   195 SAHAQLQDLLEHYTECPLS 213
Cdd:smart00252  66 RKFPSLVELVEHYQKNSLG 84

Src homology 2 domain found in the SH2 domain containing protein 2A and 7 (SH2D2A and SH2D7); SH2D2A and SH7 both contain a single SH2 domain. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 115 LWFHGFITRREAERLLQPQPLGCYLVRFSESAVTFVLSYslvgeemasltqsgpsRSQTCCRHFLLAQLGDGRHVVLGED 194
Cdd:cd10349    1 AWFHGFITRREAERLLEPKPQGCYLVRFSESAVTFVLSY----------------RSRTCCRHFLLAQLRDGRHVVLGED 64

                         90
                 ....*....|...
gi 568922944 195 SAHAQLQDLLEHY 207
Cdd:cd10349   65 SAHARLQDLLLHY 77

Src homology 2 domain found in hematopoietic SH2 (HSH2) protein; HSH2 is thought to function as an adapter protein involved in tyrosine kinase signaling. It may also be involved in regulating cytokine signaling and cytoskeletal reorganization in hematopoietic cells. HSH2 contains several putative protein-binding motifs, SH3-binding proline-rich regions, and phosphotyrosine sites, but lacks enzymatic motifs. HSH2 was found to interact with cytokine-regulated tyrosine kinase c-FES and an activated Cdc42-associated tyrosine kinase ACK1. HSH2 binds c-FES through both its C-terminal region and its N-terminal region including the SH2 domain and binds ACK1 via its N-terminal proline-rich region. Both kinases bound and tyrosine-phosphorylated HSH2 in mammalian cells. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 114 PLWFHGFITRREAERLLQPQPLGCYLVRFSESAVTFVLSYslvgeemasltqsgpsRSQTCCRHFLLAQLGDGRHVVLGE 193
Cdd:cd09946    7 PEWFHGAISREAAENMLESQPLGSFLIRVSHSHVGYTLSY----------------KAQSSCRHFMVKLLDDGTFMIPGE 70

                         90       100
                 ....*....|....*....|....*....
gi 568922944 194 DSAHAQLQDLLEHYTECPLSPYGEILTQP 222
Cdd:cd09946   71 KVAHTSLHALVTFHQQKPIEPRRELLTQA 99

Src homology 2 domains; Src homology 2 domains bind phosphotyrosine-containing polypeptides via 2 surface pockets. Specificity is provided via interaction with residues that are distinct from the phosphotyrosine. Only a single occurrence of a SH2 domain has been found in S. cerevisiae.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944   116 WFHGFITRREAERLLQPQPLGCYLVRFSES-AVTFVLSYslvgeemasltqsgpsRSQTCCRHFLLAQLGDGRhVVLGED 194
Cdd:smart00252   3 WYHGFISREEAEKLLKNEGDGDFLVRDSESsPGDYVLSV----------------RVKGKVKHYRIRRNEDGK-FYLEGG 65

                           90
                   ....*....|....*....
gi 568922944   195 SAHAQLQDLLEHYTECPLS 213
Cdd:smart00252  66 RKFPSLVELVEHYQKNSLG 84

Src homology 2 domain found in the SH2 domain containing protein 4B (SH2D4B); SH2D4B contains a single SH2 domain. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 111 KTAPLWFHGFITRREAERLLQPQPLGCYLVRFSESAVTFVLSYslvgeemasltqsgpsRSQTCCRHFLLAQLGDgRHVV 190
Cdd:cd10351    4 KTIAPWFHGIISREEAEALLMNATEGSFLVRVSEKIWGYTLSY----------------RLQSGFKHFLVDASGD-FYSF 66

                         90       100       110
                 ....*....|....*....|....*....|....*..
gi 568922944 191 LGED-SAHAQLQDLLE-HYTECPLSPYGEILTQPLAR 225
Cdd:cd10351   67 LGVDpNRHATLTDLIDfHKEEIITTSGGELLQEPCGQ 103

Src homology 2 domain found in SH2 domain-containing adapter proteins B, D, E, and F (SHB, SHD, SHE, SHF); SHB, SHD, SHE, and SHF are SH2 domain-containing proteins that play various roles throughout the cell. SHB functions in generating signaling compounds in response to tyrosine kinase activation. SHB contains proline-rich motifs, a phosphotyrosine binding (PTB) domain, tyrosine phosphorylation sites, and a SH2 domain. SHB mediates certain aspects of platelet-derived growth factor (PDGF) receptor-, fibroblast growth factor (FGF) receptor-, neural growth factor (NGF) receptor TRKA-, T cell receptor-, interleukin-2 (IL-2) receptor- and focal adhesion kinase- (FAK) signaling. SRC-like FYN-Related Kinase FRK/RAK (also named BSK/IYK or GTK) and SHB regulate apoptosis, proliferation and differentiation. SHB promotes apoptosis and is also required for proper mitogenicity, spreading and tubular morphogenesis in endothelial cells. SHB also plays a role in preventing early cavitation of embryoid bodies and reduces differentiation to cells expressing albumin, amylase, insulin and glucagon. SHB is a multifunctional protein that has difference responses in different cells under various conditions. SHE is expressed in heart, lung, brain, and skeletal muscle, while expression of SHD is restricted to the brain. SHF is mainly expressed in skeletal muscle, brain, liver, prostate, testis, ovary, small intestine, and colon. SHD may be a physiological substrate of c-Abl and may function as an adapter protein in the central nervous system. It is also thought to be involved in apoptotic regulation. SHD contains five YXXP motifs, a substrate sequence preferred by Abl tyrosine kinases, in addition to a poly-proline rich region and a C-terminal SH2 domain. SHE contains two pTry protein binding domains, protein interaction domain (PID) and a SH2 domain, followed by a glycine-proline rich region, all of which are N-terminal to the phosphotyrosine binding (PTB) domain. SHF contains four putative tyrosine phosphorylation sites and an SH2 domain. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 116 WFHGFITRREAERLLQPQPLGCYLVRFSESAvtfVLSYSLvgeemaSLtqsgpsRSQTCCRHFLLAQLGDGRhVVLGEDS 195
Cdd:cd09945    3 WYHGAITRIEAESLLRPCKEGSYLVRNSEST---KQDYSL------SL------KSAKGFMHMRIQRNETGQ-YILGQFS 66

                         90
                 ....*....|....*...
gi 568922944 196 A-HAQLQDLLEHYTECPL 212
Cdd:cd09945   67 RpFETIPEMIRHYCLNKL 84

Src homology 2 (SH2) domain found in the Src family of non-receptor tyrosine kinases; The Src family kinases are nonreceptor tyrosine kinases that have been implicated in pathways regulating proliferation, angiogenesis, invasion and metastasis, and bone metabolism. It is thought that transforming ability of Src is linked to its ability to activate key signaling molecules in these pathways, rather than through direct activity. As such blocking Src activation has been a target for drug companies. Src family members can be divided into 3 groups based on their expression pattern: 1) Src, Fyn, and Yes; 2) Blk, Fgr, Hck, Lck, and Lyn; and 3) Frk-related kinases Frk/Rak and Iyk/Bsk Of these, cellular c-Src is the best studied and most frequently implicated in oncogenesis. The c-Src contains five distinct regions: a unique N-terminal domain, an SH3 domain, an SH2 domain, a kinase domain and a regulatory tail, as do the other members of the family. Src exists in both active and inactive conformations. Negative regulation occurs through phosphorylation of Tyr, resulting in an intramolecular association between phosphorylated Tyr and the SH2 domain of SRC, which locks the protein in a closed conformation. Further stabilization of the inactive state occurs through interactions between the SH3 domain and a proline-rich stretch of residues within the kinase domain. Conversely, dephosphorylation of Tyr allows SRC to assume an open conformation. Full activity requires additional autophosphorylation of a Tyr residue within the catalytic domain. Loss of the negative-regulatory C-terminal segment has been shown to result in increased activity and transforming potential. Phosphorylation of the C-terminal Tyr residue by C-terminal Src kinase (Csk) and Csk homology kinase results in increased intramolecular interactions and consequent Src inactivation. Specific phosphatases, protein tyrosine phosphatase a (PTPa) and the SH-containing phosphatases SHP1/SHP2, have also been shown to take a part in Src activation. Src is also activated by direct binding of focal adhesion kinase (Fak) and Crk-associated substrate (Cas) to the SH2 domain. SRC activity can also be regulated by numerous receptor tyrosine kinases (RTKs), such as Her2, epidermal growth factor receptor (EGFR), fibroblast growth factor receptor, platelet-derived growth factor receptor (PDGFR), and vascular endothelial growth factor receptor (VEGFR). In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 116 WFHGFITRREAER-LLQP-QPLGCYLVRFSESAV-TFVLSyslvgeemaslTQSGPSRSQTCCRHFLLAQLGDGRHVVlg 192
Cdd:cd09933    5 WFFGKIKRKDAEKlLLAPgNPRGTFLIRESETTPgAYSLS-----------VRDGDDARGDTVKHYRIRKLDNGGYYI-- 71

                         90       100
                 ....*....|....*....|
gi 568922944 193 edSAHAQ---LQDLLEHYTE 209
Cdd:cd09933   72 --TTRATfptLQELVQHYSK 89

C-terminal Src homology 2 (C-SH2) domain found in SH2 domain Phosphatases (SHP) proteins; The SH2 domain phosphatases (SHP-1, SHP-2/Syp, Drosophila corkscrew (csw), and Caenorhabditis elegans Protein Tyrosine Phosphatase (Ptp-2)) are cytoplasmic signaling enzymes. They are both targeted and regulated by interactions of their SH2 domains with phosphotyrosine docking sites. These proteins contain two SH2 domains (N-SH2, C-SH2) followed by a tyrosine phosphatase (PTP) domain, and a C-terminal extension. Shp1 and Shp2 have two tyrosyl phosphorylation sites in their C-tails, which are phosphorylated differentially by receptor and nonreceptor PTKs. Csw retains the proximal tyrosine and Ptp-2 lacks both sites. Shp-binding proteins include receptors, scaffolding adapters, and inhibitory receptors. Some of these bind both Shp1 and Shp2 while others bind only one. Most proteins that bind a Shp SH2 domain contain one or more immuno-receptor tyrosine-based inhibitory motifs (ITIMs): [SIVL]xpYxx[IVL]. Shp1 N-SH2 domain blocks the catalytic domain and keeps the enzyme in the inactive conformation, and is thus believed to regulate the phosphatase activity of SHP-1. Its C-SH2 domain is thought to be involved in searching for phosphotyrosine activators. The SHP2 N-SH2 domain is a conformational switch; it either binds and inhibits the phosphatase, or it binds phosphoproteins and activates the enzyme. The C-SH2 domain contributes binding energy and specificity, but it does not have a direct role in activation. Csw SH2 domain function is essential, but either SH2 domain can fulfill this requirement. The role of the csw SH2 domains during Sevenless receptor tyrosine kinase (SEV) signaling is to bind Daughter of Sevenless rather than activated SEV. Ptp-2 acts in oocytes downstream of sheath/oocyte gap junctions to promote major sperm protein (MSP)-induced MAP Kinase (MPK-1) phosphorylation. Ptp-2 functions in the oocyte cytoplasm, not at the cell surface to inhibit multiple RasGAPs, resulting in sustained Ras activation. It is thought that MSP triggers PTP-2/Ras activation and ROS production to stimulate MPK-1 activity essential for oocyte maturation and that secreted MSP domains and Cu/Zn superoxide dismutases function antagonistically to control ROS and MAPK signaling. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 116 WFHGFITRREAERLLQPQPL-GCYLVRFSESAV-TFVLSYsLVGEEMASltqsgpsrsqtccrHFLLAQLGDGRHVVLGE 193
Cdd:cd09931    2 WFHGHLSGKEAEKLLLEKGKpGSFLVRESQSKPgDFVLSV-RTDDDKVT--------------HIMIRCQGGKYDVGGGE 66

                         90       100       110
                 ....*....|....*....|....*....|....*
gi 568922944 194 --DSahaqLQDLLEHYTECPLSPY-GEI--LTQPL 223
Cdd:cd09931   67 efDS----LTDLVEHYKKNPMVETsGTVvhLKQPL 97

Src homology 2 (SH2) domain found in feline sarcoma, Fujinami poultry sarcoma, and fes-related (Fes/Fps/Fer) proteins; The Fps family consists of members Fps/Fes and Fer/Flk/Tyk3. They are cytoplasmic protein-tyrosine kinases implicated in signaling downstream from cytokines, growth factors and immune receptors. Fes/Fps/Fer contains three coiled-coil regions, an SH2 (Src-homology-2) and a TK (tyrosine kinase catalytic) domain signature. Members here include: Fps/Fes, Fer, Kin-31, and In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 116 WFHGFITRREAERLLQPQplGCYLVRFSESAVT----FVLSYsLVGEEmasltqsgpsrsqtcCRHFLLAQLGDGRHVVl 191
Cdd:cd10361    8 YYHGLLPREDAEELLKND--GDFLVRKTEPKGGgkrkLVLSV-RWDGK---------------IRHFVINRDDGGKYYI- 68

                         90
                 ....*....|....*...
gi 568922944 192 gEDSAHAQLQDLLEHYTE 209
Cdd:cd10361   69 -EGKSFKSISELINYYQK 85

N-terminal Src homology 2 (SH2) domain found in SH2 domains, ANK, and kinase domain (shark) proteins; These non-receptor protein-tyrosine kinases contain two SH2 domains, five ankyrin (ANK)-like repeats, and a potential tyrosine phosphorylation site in the carboxyl-terminal tail which resembles the phosphorylation site in members of the src family. Like, mammalian non-receptor protein-tyrosine kinases, ZAP-70 and syk proteins, they do not have SH3 domains. However, the presence of ANK makes these unique among protein-tyrosine kinases. Both tyrosine kinases and ANK repeats have been shown to transduce developmental signals, and SH2 domains are known to participate intimately in tyrosine kinase signaling. These tyrosine kinases are believed to be involved in epithelial cell polarity. The members of this family include the shark (SH2 domains, ANK, and kinase domain) gene in Drosophila and yellow fever mosquitos, as well as the hydra protein HTK16. Drosophila Shark is proposed to transduce intracellularly the Crumbs, a protein necessary for proper organization of ectodermal epithelia, intercellular signal. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 115 LWFHGFITRREAERLLQPQPL--GCYLVRFSESAV-TFVLSYSLVGEemasltqsgpsrsqtcCRHFLLAQLGDGRHVVL 191
Cdd:cd10347    2 RWYHGKISREVAEALLLREGGrdGLFLVRESTSAPgDYVLSLLAQGE----------------VLHYQIRRHGEDAFFSD 65

                         90
                 ....*....|....*.
gi 568922944 192 GEDSAHAQLQDLLEHY 207
Cdd:cd10347   66 DGPLIFHGLDTLIEHY 81

C-terminal Src homology 2 (C-SH2) domain in Phospholipase C gamma; Phospholipase C gamma is a signaling molecule that is recruited to the C-terminal tail of the receptor upon autophosphorylation of a highly conserved tyrosine. PLCgamma is composed of a Pleckstrin homology (PH) domain followed by an elongation factor (EF) domain, 2 catalytic regions of PLC domains that flank 2 tandem SH2 domains (N-SH2, C-SH2), and ending with a SH3 domain and C2 domain. N-SH2 SH2 domain-mediated interactions represent a crucial step in transmembrane signaling by receptor tyrosine kinases. SH2 domains recognize phosphotyrosine (pY) in the context of particular sequence motifs in receptor phosphorylation sites. Both N-SH2 and C-SH2 have a very similar binding affinity to pY. But in growth factor stimulated cells these domains bind to different target proteins. N-SH2 binds to pY containing sites in the C-terminal tails of tyrosine kinases and other receptors. Recently it has been shown that this interaction is mediated by phosphorylation-independent interactions between a secondary binding site found exclusively on the N-SH2 domain and a region of the FGFR1 tyrosine kinase domain. This secondary site on the SH2 cooperates with the canonical pY site to regulate selectivity in mediating a specific cellular process. C-SH2 binds to an intramolecular site on PLCgamma itself which allows it to hydrolyze phosphatidylinositol-4,5-bisphosphate into diacylglycerol and inositol triphosphate. These then activate protein kinase C and release calcium. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 116 WFHGFITRREAERLLQPQPL-GCYLVRFSE-SAVTFVLSYslvgeemasltqsgpsRSQTCCRHFLLAQlgDGRHVVLGe 193
Cdd:cd09932    6 WFHANLTREQAEEMLMRVPRdGAFLVRPSEtDPNSFAISF----------------RAEGKIKHCRIKQ--EGRLFVIG- 66

                         90
                 ....*....|....*....
gi 568922944 194 DSAHAQLQDLLEHYTECPL 212
Cdd:cd09932   67 TSQFESLVELVSYYEKHPL 85

Src homology 2 (SH2) domain found in Nck; Nck proteins are adaptors that modulate actin cytoskeleton dynamics by linking proline-rich effector molecules to tyrosine kinases or phosphorylated signaling intermediates. There are two members known in this family: Nck1 (Nckalpha) and Nck2 (Nckbeta and Growth factor receptor-bound protein 4 (Grb4)). They are characterized by having 3 SH3 domains and a C-terminal SH2 domain. Nck1 and Nck2 have overlapping functions as determined by gene knockouts. Both bind receptor tyrosine kinases and other tyrosine-phosphorylated proteins through their SH2 domains. In addition they also bind distinct targets. Neuronal signaling proteins: EphrinB1, EphrinB2, and Disabled-1 (Dab-1) all bind to Nck-2 exclusively. And in the case of PDGFR, Tyr(P)751 binds to Nck1 while Tyr(P)1009 binds to Nck2. Nck1 and Nck2 have a role in the infection process of enteropathogenic Escherichia coli (EPEC). Their SH3 domains are involved in recruiting and activating the N-WASP/Arp2/3 complex inducing actin polymerization resulting in the production of pedestals, dynamic bacteria-presenting protrusions of the plasma membrane. A similar thing occurs in the vaccinia virus where motile plasma membrane projections are formed beneath the virus. Recently it has been shown that the SH2 domains of both Nck1 and Nck2 bind the G-protein coupled receptor kinase-interacting protein 1 (GIT1) in a phosphorylation-dependent manner. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 116 WFHGFITRREAERLLQPQPL-GCYLVRFSESAVT-FVLSYSLVGEEmasltqsgpsrsqtccRHFLLaQLGDGRHVVlGE 193
Cdd:cd10409    3 WYYGNVTRHQAECALNERGVeGDFLIRDSESSPSdFSVSLKAVGKN----------------KHFKV-QLVDNVYCI-GQ 64

                         90       100
                 ....*....|....*....|....*...
gi 568922944 194 DSAHAqLQDLLEHYTECPL--SPYGEIL 219
Cdd:cd10409   65 RRFNS-MDELVEHYKKAPIftSEHGEKL 91

Src homology 2 (SH2) domain found in SH2 adaptor protein C (SHC); SHC is involved in a wide variety of pathways including regulating proliferation, angiogenesis, invasion and metastasis, and bone metabolism. An adapter protein, SHC has been implicated in Ras activation following the stimulation of a number of different receptors, including growth factors [insulin, epidermal growth factor (EGF), nerve growth factor, and platelet derived growth factor (PDGF)], cytokines [interleukins 2, 3, and 5], erythropoietin, and granulocyte/macrophage colony-stimulating factor, and antigens [T-cell and B-cell receptors]. SHC has been shown to bind to tyrosine-phosphorylated receptors, and receptor stimulation leads to tyrosine phosphorylation of SHC. Upon phosphorylation, SHC interacts with another adapter protein, Grb2, which binds to the Ras GTP/GDP exchange factor mSOS which leads to Ras activation. SHC is composed of an N-terminal domain that interacts with proteins containing phosphorylated tyrosines, a (glycine/proline)-rich collagen-homology domain that contains the phosphorylated binding site, and a C-terminal SH2 domain. SH2 has been shown to interact with the tyrosine-phosphorylated receptors of EGF and PDGF and with the tyrosine-phosphorylated C chain of the T-cell receptor, providing one of the mechanisms of T-cell-mediated Ras activation. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|
gi 568922944 116 WFHGFITRREAERLLQPQplGCYLVRfsESAVT---FVLS 152
Cdd:cd09925    9 WYHGKMSRRDAESLLQTD--GDFLVR--ESTTTpgqYVLT 44

Src homology 2 (SH2) domain found in SH2 domain-bearing protein kinases A and C (ShkA and ShkC); SH2-bearing genes cloned from Dictyostelium include two transcription factors, STATa and STATc, and a signaling factor, SHK1 (shkA). A database search of the Dictyostelium discoideum genome revealed two additional putative STAT sequences, dd-STATb and dd-STATd, and four additional putative SHK genes, dd-SHK2 (shkB), dd-SHK3 (shkC), dd-SHK4 (shkD), and dd-SHK5 (shkE). This model contains members of shkA and shkC. All of the SHK members are most closely related to the protein kinases found in plants. However these kinases in plants are not conjugated to any SH2 or SH2-like sequences. Alignment data indicates that the SHK SH2 domains carry some features of the STAT SH2 domains in Dictyostelium. When STATc's linker domain was used for a BLAST search, the sequence between the protein kinase domain and the SH2 domain (the linker) of SHK was recovered, suggesting a close relationship among these molecules within this region. SHK's linker domain is predicted to contain an alpha-helix which is indeed homologous to that of STAT. Based on the phylogenetic alignment, SH2 domains can be grouped into two categories, STAT-type and Src-type. SHK family members are in between, but are closer to the STAT-type which indicates a close relationship between SHK and STAT families in their SH2 domains and further supports the notion that SHKs linker-SH2 domain evolved from STAT or STATL (STAT-like Linker-SH2) domain found in plants. In SHK, STAT, and SPT6, the linker-SH2 domains all reside exclusively in the C-terminal regions. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30
                 ....*....|....*....|....*....|
gi 568922944 116 WFHGFITRREAERLLQPQPLGCYLVRFSES 145
Cdd:cd10356   12 WFHGDISTSESENRLNGKPEGTFLVRFSTS 41

C-terminal Src homology 2 (SH2) domain found in Ras GTPase-activating protein 1 (GAP); RasGAP is part of the GAP1 family of GTPase-activating proteins. The protein is located in the cytoplasm and stimulates the GTPase activity of normal RAS p21, but not its oncogenic counterpart. Acting as a suppressor of RAS function, the protein enhances the weak intrinsic GTPase activity of RAS proteins resulting in RAS inactivation, thereby allowing control of cellular proliferation and differentiation. Mutations leading to changes in the binding sites of either protein are associated with basal cell carcinomas. Alternative splicing results in two isoforms. The shorter isoform which lacks the N-terminal hydrophobic region, has the same activity, and is expressed in placental tissues. In general longer isoform contains 2 SH2 domains, a SH3 domain, a pleckstrin homology (PH) domain, and a calcium-dependent phospholipid-binding C2 domain. The C-terminus contains the catalytic domain of RasGap which catalyzes the activation of Ras by hydrolyzing GTP-bound active Ras into an inactive GDP-bound form of Ras. This model contains the C-terminal SH2 domain. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|.
gi 568922944 116 WFHGFITRREAERLL-QPQPLGCYLVRFSESAVTfvlSYSL 155
Cdd:cd10354    2 WFHGKISREEAYNMLvKVGGPGSFLVRESDNTPG---DYSL 39

Src homology 2 (SH2) domain found in HCK; HCK is a member of the Src non-receptor type tyrosine kinase family of proteins and is expressed in hemopoietic cells. HCK is proposed to couple the Fc receptor to the activation of the respiratory burst. It may also play a role in neutrophil migration and in the degranulation of neutrophils. It has two different translational starts that have different subcellular localization. HCK has been shown to interact with BCR gene, ELMO1 Cbl gene, RAS p21 protein activator 1, RASA3, Granulocyte colony-stimulating factor receptor, ADAM15 and RAPGEF1. Like the other members of the Src family the SH2 domain in addition to binding the target, also plays an autoinhibitory role by binding to its C-terminal tail. In general SH2 domains are involved in signal transduction. HCK has a unique N-terminal domain, an SH3 domain, an SH2 domain, a kinase domain and a regulatory tail, as do the other members of the family. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 568922944 116 WFHGFITRREAER-LLQP-QPLGCYLVRFSEsavTFVLSYSLvgeemaSLTQSGPSRSQTcCRHFLLAQLGDGRHVVlGE 193
Cdd:cd10363    5 WFFKGISRKDAERqLLAPgNMLGSFMIRDSE---TTKGSYSL------SVRDYDPQHGDT-VKHYKIRTLDNGGFYI-SP 73

                         90
                 ....*....|....
gi 568922944 194 DSAHAQLQDLLEHY 207
Cdd:cd10363   74 RSTFSTLQELVDHY 87

Src homology 2 (SH2) domain found in the Nck family; Nck proteins are adaptors that modulate actin cytoskeleton dynamics by linking proline-rich effector molecules to tyrosine kinases or phosphorylated signaling intermediates. There are two members known in this family: Nck1 (Nckalpha) and Nck2 (Nckbeta and Growth factor receptor-bound protein 4 (Grb4)). They are characterized by having 3 SH3 domains and a C-terminal SH2 domain. Nck1 and Nck2 have overlapping functions as determined by gene knockouts. Both bind receptor tyrosine kinases and other tyrosine-phosphorylated proteins through their SH2 domains. In addition they also bind distinct targets. Neuronal signaling proteins: EphrinB1, EphrinB2, and Disabled-1 (Dab-1) all bind to Nck-2 exclusively. And in the case of PDGFR, Tyr(P)751 binds to Nck1 while Tyr(P)1009 binds to Nck2. Nck1 and Nck2 have a role in the infection process of enteropathogenic Escherichia coli (EPEC). Their SH3 domains are involved in recruiting and activating the N-WASP/Arp2/3 complex inducing actin polymerization resulting in the production of pedestals, dynamic bacteria-presenting protrusions of the plasma membrane. A similar thing occurs in the vaccinia virus where motile plasma membrane projections are formed beneath the virus. Recently it has been shown that the SH2 domains of both Nck1 and Nck2 bind the G-protein coupled receptor kinase-interacting protein 1 (GIT1) in a phosphorylation-dependent manner. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

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gi 568922944 116 WFHGFITRREAERLLQPQPL-GCYLVRFSESAvtfvlsyslVGEEMASLTQSGPSrsqtccRHFLLaQLGDGRHVVlGED 194
Cdd:cd09943    3 WYYGRITRHQAETLLNEHGHeGDFLIRDSESN---------PGDYSVSLKAPGRN------KHFKV-QVVDNVYCI-GQR 65

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gi 568922944 195 SAHAqLQDLLEHYTECPL--SPYGEIL 219
Cdd:cd09943   66 KFHT-MDELVEHYKKAPIftSEQGEKL 91

Src homology 2 (SH2) domain found in signal transducer and activator of transcription (STAT) 3 proteins; STAT3 encoded by this gene is a member of the STAT protein family. STAT3 mediates the expression of a variety of genes in response to cell stimuli, and plays a key role in many cellular processes such as cell growth and apoptosis. The small GTPase Rac1 regulates the activity of STAT3 and PIAS3 inhibits it. Three alternatively spliced transcript variants encoding distinct isoforms have been described. STAT 3 activation is required for self-renewal of embryonic stem cells (ESCs) and is essential for the differentiation of the TH17 helper T cells. Mutations in the STAT3 gene result in Hyperimmunoglobulin E syndrome and human cancers. STAT3 has been shown to interact with Androgen receptor, C-jun, ELP2, EP300, Epidermal growth factor receptor, Glucocorticoid receptor, HIF1A, Janus kinase 1, KHDRBS1, Mammalian target of rapamycin, MyoD, NDUFA13, NFKB1, Nuclear receptor coactivator 1, Promyelocytic leukemia protein, RAC1, RELA, RET proto-oncogene, RPA2, Src, STAT1, and TRIP10. STAT proteins mediate the signaling of cytokines and a number of growth factors from the receptors of these extracellular signaling molecules to the cell nucleus. STATs are specifically phosphorylated by receptor-associated Janus kinases, receptor tyrosine kinases, or cytoplasmic tyrosine kinases. The phosphorylated STAT molecules dimerize by reciprocal binding of their SH2 domains to the phosphotyrosine residues. These dimeric STATs translocate into the nucleus, bind to specific DNA sequences, and regulate the transcription of their target genes. However there are a number of unphosphorylated STATs that travel between the cytoplasm and nucleus and some STATs that exist as dimers in unstimulated cells that can exert biological functions independent of being activated. There are seven mammalian STAT family members which have been identified: STAT1, STAT2, STAT3, STAT4, STAT5 (STAT5A and STAT5B), and STAT6. There are 6 conserved domains in STAT: N-terminal domain (NTD), coiled-coil domain (CCD), DNA-binding domain (DBD), alpha-helical linker domain (LD), SH2 domain, and transactivation domain (TAD). NTD is involved in dimerization of unphosphorylated STATs monomers and for the tetramerization between STAT1, STAT3, STAT4 and STAT5 on promoters with two or more tandem STAT binding sites. It also plays a role in promoting interactions with transcriptional co-activators such as CREB binding protein (CBP)/p300, as well as being important for nuclear import and deactivation of STATs involving tyrosine de-phosphorylation. CCD interacts with other proteins, such as IFN regulatory protein 9 (IRF-9/p48) with STAT1 and c-JUN with STAT3 and is also thought to participate in the negative regulation of these proteins. Distinct genes are bound to STATs via their DBD domain. This domain is also involved in nuclear translocation of activated STAT1 and STAT3 phosphorylated dimers upon cytokine stimulation. LD links the DNA-binding and SH2 domains and is important for the transcriptional activation of STAT1 in response to IFN-gamma. It also plays a role in protein-protein interactions and has also been implicated in the constitutive nucleocytoplasmic shuttling of unphosphorylated STATs in resting cells. The SH2 domain is necessary for receptor association and tyrosine phosphodimer formation. Residues within this domain may be particularly important for some cellular functions mediated by the STATs as well as residues adjacent to this domain. The TAD interacts with several proteins, namely minichromosome maintenance complex component 5 (MCM5), breast cancer 1 (BRCA1) and CBP/p300. TAD also contains a modulatory phosphorylation site that regulates STAT activity and is necessary for maximal transcription of a number of target genes. The conserved tyrosine residue present in the C-terminus is crucial for dimerization via interaction with the SH2 domain upon the interaction of the ligand with the receptor. STAT activation by tyrosine phosphorylation also determines nuclear import and retention, DNA binding to specific DNA elements in the promoters of responsive genes, and transcriptional activation of STAT dimers. In addition to the SH2 domain there is a coiled-coil domain, a DNA binding domain, and a transactivation domain in the STAT proteins. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

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gi 568922944 119 GFITRREAERLLQPQPLGCYLVRFSESAVTFVLSYSLVGEEMASLTQ 165
Cdd:cd10374   34 GFISKERERAILSTKPPGTFLLRFSESSKEGGVTFTWVEKDISGKTQ 80

Src homology 2 (SH2) domain found in tyrosine kinase sarcoma (Src); Src is a member of the Src non-receptor type tyrosine kinase family of proteins. Src is thought to play a role in the regulation of embryonic development and cell growth. Members here include v-Src and c-Src. v-Src lacks the C-terminal inhibitory phosphorylation site and is therefore constitutively active as opposed to normal cellular src (c-Src) which is only activated under certain circumstances where it is required (e.g. growth factor signaling). v-Src is an oncogene whereas c-Src is a proto-oncogene. c-Src consists of three domains, an N-terminal SH3 domain, a central SH2 domain and a tyrosine kinase domain. The SH2 and SH3 domains work together in the auto-inhibition of the kinase domain. The phosphorylation of an inhibitory tyrosine near the c-terminus of the protein produces a binding site for the SH2 domain which then facilitates binding of the SH3 domain to a polyproline site within the linker between the SH2 domain and the kinase domain. Binding of the SH3 domain inactivates the enzyme. This allows for multiple mechanisms for c-Src activation: dephosphorylation of the C-terminal tyrosine by a protein tyrosine phosphatase, binding of the SH2 domain by a competitive phospho-tyrosine residue, or competitive binding of a polyproline binding site to the SH3 domain. Unlike most other Src members Src lacks cysteine residues in the SH4 domain that undergo palmitylation. Serine and threonine phosphorylation sites have also been identified in the unique domains of Src and are believed to modulate protein-protein interactions or regulate catalytic activity. Alternatively spliced forms of Src, which contain 6- or 11-amino acid insertions in the SH3 domain, are expressed in CNS neurons. c-Src has a unique N-terminal domain, an SH3 domain, an SH2 domain, a kinase domain and a regulatory tail, as do the other members of the family. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

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gi 568922944 116 WFHGFITRREAER-LLQPQ-PLGCYLVRFSES 145
Cdd:cd10365    5 WYFGKITRRESERlLLNAEnPRGTFLVRESET 36

Src homology 2 (SH2) domain found in suppressor of cytokine signaling (SOCS) proteins; SH2 domain found in SOCS proteins. SOCS was first recognized as a group of cytokine-inducible SH2 (CIS) domain proteins comprising eight family members in human (CIS and SOCS1-SOCS7). In addition to the SH2 domain, SOCS proteins have a variable N-terminal domain and a conserved SOCS box in the C-terminal domain. SOCS proteins bind to a substrate via their SH2 domain. The prototypical members, CIS and SOCS1-SOCS3, have been shown to regulate growth hormone signaling in vitro and in a classic negative feedback response compete for binding at phosphotyrosine sites in JAK kinase and receptor pathways to displace effector proteins and target bound receptors for proteasomal degradation. Loss of SOCS activity results in excessive cytokine signaling associated with a variety of hematopoietic, autoimmune, and inflammatory diseases and certain cancers. Members (SOCS4-SOCS7) were identified by their conserved SOCS box, an adapter motif of 3 helices that associates substrate binding domains, such as the SOCS SH2 domain, ankryin, and WD40 with ubiquitin ligase components. These show limited cytokine induction. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

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gi 568922944 107 WLLLKTAPL-WFHGFITRREAERLLQPQPLGCYLVRFSeSAVTFVLSYS 154
Cdd:cd10387    2 EELKKLAKQgWYWGPITRWEAEGKLANVPDGSFLVRDS-SDDRYLLSLS 49

Src homology 2 (SH2) domain found in Tec-like proteins; The Tec protein tyrosine kinase is the founding member of a family that includes Btk, Itk, Bmx, and Txk. The members have a PH domain, a zinc-binding motif, a SH3 domain, a SH2 domain, and a protein kinase catalytic domain. Btk is involved in B-cell receptor signaling with mutations in Btk responsible for X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (xid) in mice. Itk is involved in T-cell receptor signaling. Tec is expressed in both T and B cells, and is thought to function in activated and effector T lymphocytes to induce the expression of genes regulated by NFAT transcription factors. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

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gi 568922944 116 WFHGFITRREAERLL-QPQPLGCYLVRFSESAVTFVLS 152
Cdd:cd09934    8 WYVGDMSRQRAESLLkQEDKEGCFVVRNSSTKGLYTVS 45

Src homology 2 (SH2) domain found in Ras and Rab interactor 2 (RIN2)-like proteins; RIN2, a member of the RIN (AKA Ras interaction/interference) family, have multifunctional domains including SH2 and proline-rich (PR) domains in the N-terminal region, and RIN-family homology (RH), VPS9 and Ras-association (RA) domains in the C-terminal region. RIN proteins function as Rab5-GEFs. Ras induces activation of Rab5 through RIN2, which is a direct downstream target of Ras and a direct upstream regulator of Rab5. In other words it is the binding of the GTP-bound form of Ras to the RA domain of RIN2 that enhances the GEF activity toward Rab5. It is thought that the RA domain negatively regulates the Rab5 GEF activity. In steady state, RIN2 is likely to form a closed conformation by an intramolecular interaction between the RA domain and the Vps9p-like (Rab5 GEF) domain, negatively regulating the Rab5 GEF activity. In the active state, the binding of Ras to the RA domain may reduce the intramolecular interaction and stabilize an open conformation of RIN2. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

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gi 568922944 109 LLKTAPLWFHGFITRREAERLLQPQPLGCYLVRFSESAVTFVLSYSLvgeemasltqsgPSRSQTCCRHF 178
Cdd:cd10394    5 LLHTHPIWLQLSLSEEEAAEVLQAQPPGIFLVRKSSKMQKKVLSLRL------------PCEFGAPLKEF 62

Src homology 2 domain found in SH2 domain-containing adapter proteins D (SHD); The expression of SHD is restricted to the brain. SHD may be a physiological substrate of c-Abl and may function as an adapter protein in the central nervous system. It is also thought to be involved in apoptotic regulation. SHD contains five YXXP motifs, a substrate sequence preferred by Abl tyrosine kinases, in addition to a poly-proline rich region and a C-terminal SH2 domain. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

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gi 568922944 116 WFHGFITRREAERLLQPQPLGCYLVRFSES 145
Cdd:cd10390    3 WFHGPLSRADAENLLSLCKEGSYLVRLSET 32

Src homology 2 (SH2) domain found in alpha2-chimerin and beta2-chimerin proteins; Chimerins are a family of phorbol ester- and diacylglycerol-responsive GTPase-activating proteins. Alpha1-chimerin (formerly known as n-chimerin) and alpha2-chimerin are alternatively spliced products of a single gene, as are beta1- and beta2-chimerin. alpha1- and beta1-chimerin have a relatively short N-terminal region that does not encode any recognizable domains, whereas alpha2- and beta2-chimerin both include a functional SH2 domain that can bind to phosphotyrosine motifs within receptors. All of the isoforms contain a GAP domain with specificity in vitro for Rac1 and a diacylglycerol (DAG)-binding C1 domain which allows them to translocate to membranes in response to DAG signaling and anchors them in close proximity to activated Rac. Other C1 domain-containing diacylglycerol receptors including: PKC, Munc-13 proteins, phorbol ester binding scaffolding proteins involved in Ca2+-stimulated exocytosis, and RasGRPs, diacylglycerol-activated guanine-nucleotide exchange factors (GEFs) for Ras and Rap1. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

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gi 568922944 117 FHGFITRREAERLLQPQPLGCYLVRFSESA 146
Cdd:cd10352    9 YHGLISREEAEQLLSGASDGSYLIRESSRD 38

C-terminal Src homology 2 (SH2) domain found in SH2 domains, ANK, and kinase domain (shark) proteins; These non-receptor protein-tyrosine kinases contain two SH2 domains, five ankyrin (ANK)-like repeats, and a potential tyrosine phosphorylation site in its carboxyl-terminal tail which resembles the phosphorylation site in members of the src family. Like, mammalian non-receptor protein-tyrosine kinases, ZAP-70 and syk proteins, they do not have SH3 domains. However, the presence of ANK makes these unique among protein-tyrosine kinases. Both tyrosine kinases and ANK repeats have been shown to transduce developmental signals, and SH2 domains are known to participate intimately in tyrosine kinase signaling. These tyrosine kinases are believed to be involved in epithelial cell polarity. The members of this family include the shark (SH2 domains, ANK, and kinase domain) gene in Drosophila and yellow fever mosquitos, as well as the hydra protein HTK16. Drosophila Shark is proposed to transduce intracellularly the Crumbs, a protein necessary for proper organization of ectodermal epithelia, intercellular signal. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites.

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gi 568922944 116 WFHGFITRREAERLLQPQPL--GCYLVRFSES-AVTFVLS 152
Cdd:cd10348    2 WLHGALDRNEAVEILKQKADadGSFLVRYSRRrPGGYVLT 41