SH2B adapter protein 1, 2, and 3 Pleckstrin homology (PH) domain; SH2B family/APS proteins are a family of intracellular adaptor proteins that influences a variety of signaling pathways mediated by Janus kinase (JAK) and receptor tyrosine kinases (RTKs) including receptors for insulin, insulin-like growth factor-1, Janus kinase 2 (Jak2), platelet derived growth factor, fibroblast growth factor and nerve growth factor. They function in glucose homeostasis, energy metabolism, hematopoesis and reproduction. Mutations in human SH2B orthologs are associated with metabolic disregulation and obesity. There are several SH2B members in mammals: SH2B1 (splice variants: SH2B1alpha, SH2B1beta, SH2B1gamma, and SH2B1delta), SH2B2 (APS) and SH2B3 (Lnk). They contain a PH domain, a SH2 domain, a proline rich region, multiple consensus sites for tyrosine and serine/threonine phosphorylation and a highly conserved c-Cbl recognition motif. These domains function as protein-protein interaction motifs which allows SH2B proteins to integrate and transduce intracellular signals from multiple signaling networks in the absence of intrinsic catalytic activity. SH2B proteins bind via their SH2 domains to phosphotyrosine residues within the intracellular tails of several activated RTKs thereby contributing to receptor activation. SH2B proteins have been shown to interact with insulin receptor substrates IRS1 and IRS2, Grb2, Shc and c-Cbl which may or may not require RTK-stimulated tyrosine phosphorylation of SH2B. positively and negatively regulating RTK signaling. Understanding the physiological functions of SH2B proteins in mammals has been complicated by the presence of multiple SH2B isoforms and conflicting data. Both SH2-Bbeta and APS associate with JAKs, but the former facilitates JAK/STAT signaling while the latter inhibits it. Lnk plays a role in cell growth and proliferation with mutations resulting in growth reduction, developmental delay and female sterility. Recently Lnk Drosophila has been shown to be an important regulator of the insulin/insulin-like growth factor (IGF)-1 signaling (IIS) pathway during growth. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 728050533 186 DIQREGALRFMVADDAASGpgGTAQWQKCRLLLRRAVAGER-FRLEFFVPPKASRPKVSIPLSAIIEVRTTMPLEMPEKD 264
Cdd:cd01231    1 ECRKEGIVNYLSGEETASD--GGPRWQKCRLVLVKAAGGEGeYLLEFYVPPKSSKPKLGIFCSLIQEVRETTALEMPDNE 78

                         90       100       110
                 ....*....|....*....|....*....|....*..
gi 728050533 265 NTFVLKVENGAEYILETIDSLQKHSWVADIQGCVDPG 301
Cdd:cd01231   79 NTFVLKVENSTEYIIEAGDEQQMRSWLAEIRECMSPG 115

SH2B adapter protein 1, 2, and 3 Pleckstrin homology (PH) domain; SH2B family/APS proteins are a family of intracellular adaptor proteins that influences a variety of signaling pathways mediated by Janus kinase (JAK) and receptor tyrosine kinases (RTKs) including receptors for insulin, insulin-like growth factor-1, Janus kinase 2 (Jak2), platelet derived growth factor, fibroblast growth factor and nerve growth factor. They function in glucose homeostasis, energy metabolism, hematopoesis and reproduction. Mutations in human SH2B orthologs are associated with metabolic disregulation and obesity. There are several SH2B members in mammals: SH2B1 (splice variants: SH2B1alpha, SH2B1beta, SH2B1gamma, and SH2B1delta), SH2B2 (APS) and SH2B3 (Lnk). They contain a PH domain, a SH2 domain, a proline rich region, multiple consensus sites for tyrosine and serine/threonine phosphorylation and a highly conserved c-Cbl recognition motif. These domains function as protein-protein interaction motifs which allows SH2B proteins to integrate and transduce intracellular signals from multiple signaling networks in the absence of intrinsic catalytic activity. SH2B proteins bind via their SH2 domains to phosphotyrosine residues within the intracellular tails of several activated RTKs thereby contributing to receptor activation. SH2B proteins have been shown to interact with insulin receptor substrates IRS1 and IRS2, Grb2, Shc and c-Cbl which may or may not require RTK-stimulated tyrosine phosphorylation of SH2B. positively and negatively regulating RTK signaling. Understanding the physiological functions of SH2B proteins in mammals has been complicated by the presence of multiple SH2B isoforms and conflicting data. Both SH2-Bbeta and APS associate with JAKs, but the former facilitates JAK/STAT signaling while the latter inhibits it. Lnk plays a role in cell growth and proliferation with mutations resulting in growth reduction, developmental delay and female sterility. Recently Lnk Drosophila has been shown to be an important regulator of the insulin/insulin-like growth factor (IGF)-1 signaling (IIS) pathway during growth. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 728050533 186 DIQREGALRFMVADDAASGpgGTAQWQKCRLLLRRAVAGER-FRLEFFVPPKASRPKVSIPLSAIIEVRTTMPLEMPEKD 264
Cdd:cd01231    1 ECRKEGIVNYLSGEETASD--GGPRWQKCRLVLVKAAGGEGeYLLEFYVPPKSSKPKLGIFCSLIQEVRETTALEMPDNE 78

                         90       100       110
                 ....*....|....*....|....*....|....*..
gi 728050533 265 NTFVLKVENGAEYILETIDSLQKHSWVADIQGCVDPG 301
Cdd:cd01231   79 NTFVLKVENSTEYIIEAGDEQQMRSWLAEIRECMSPG 115

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 728050533   407 YPWFHGTLSRVKAAQLVLAGGPrshGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHVQ-HLWFQSVFDMLRH 485
Cdd:smart00252   1 QPWYHGFISREEAEKLLKNEGD---GDFLVRDSESSPGDYVLSVRVKGKVKHYRIRRNEDGKFYLEgGRKFPSLVELVEH 77

                   ....*..
gi 728050533   486 FHTHPIP 492
Cdd:smart00252  78 YQKNSLG 84

Pleckstrin homology domain; Domain commonly found in eukaryotic signalling proteins. The domain family possesses multiple functions including the abilities to bind inositol phosphates, and various proteins. PH domains have been found to possess inserted domains (such as in PLC gamma, syntrophins) and to be inserted within other domains. Mutations in Brutons tyrosine kinase (Btk) within its PH domain cause X-linked agammaglobulinaemia (XLA) in patients. Point mutations cluster into the positively charged end of the molecule around the predicted binding site for phosphatidylinositol lipids.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 728050533   187 IQREGALRFMvaddaasGPGGTAQWQKCRLLLRRavagerFRLEFFVPPKA---SRPKVSIPLSAIiEVRTTMPLEMPEK 263
Cdd:smart00233   1 VIKEGWLYKK-------SGGGKKSWKKRYFVLFN------STLLYYKSKKDkksYKPKGSIDLSGC-TVREAPDPDSSKK 66

                           90       100       110
                   ....*....|....*....|....*....|....*.
gi 728050533   264 DNTFVLKVENGAEYILETIDSLQKHSWVADIQGCVD 299
Cdd:smart00233  67 PHCFEIKTSDRKTLLLQAESEEEREKWVEALRKAIA 102

Src homology 2 (SH2) domain found in SH2B adapter protein family; The SH2B adapter protein family has 3 members: SH2B1 (SH2-B, PSM), SH2B2 (APS), and SH2B3 (Lnk). SH2B family members contain a pleckstrin homology domain, at least one dimerization domain, and a C-terminal SH2 domain which binds to phosphorylated tyrosines in a variety of tyrosine kinases. SH2B1 and SH2B2 function in signaling pathways found downstream of growth hormone receptor and receptor tyrosine kinases, including the insulin, insulin-like growth factor-I (IGF-I), platelet-derived growth factor (PDGF), nerve growth factor, hepatocyte growth factor, and fibroblast growth factor receptors. SH2B2beta, a new isoform of SH2B2, is an endogenous inhibitor of SH2B1 and/or SH2B2 (SH2B2alpha), negatively regulating insulin signaling and/or JAK2-mediated cellular responses. SH2B3 negatively regulates lymphopoiesis and early hematopoiesis. The lnk-deficiency results in enhanced production of B cells, and expansion as well as enhanced function of hematopoietic stem cells (HSCs), demonstrating negative regulatory functions of Sh2b3/Lnk in cytokine signaling. Sh2b3/Lnk also functions in responses controlled by cell adhesion and in crosstalk between integrin- and cytokine-mediated 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 728050533 401 ELELSDYPWFHGTLSRVKAAQLVLAGGPRSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHVQHLWFQSVF 480
Cdd:cd10346    2 TAELSEYPWFHGTLSRSDAAQLVLHSGADGHGVFLVRQSETRRGEFVLTFNFQGRAKHLRLTLNEKGQCRVQHLWFPSIF 81

                         90
                 ....*....|....*.
gi 728050533 481 DMLRHFHTHPIPLESG 496
Cdd:cd10346   82 DMLEHFRQNPIPLESG 97

Src homology 2 (SH2) domain found in SH2B adapter proteins (SH2B1, SH2B2, SH2B3); SH2B1 (SH2-B, PSM), like other members of the SH2B adapter protein family, contains a pleckstrin homology domain, at least one dimerization domain, and a C-terminal SH2 domain which binds to phosphorylated tyrosines in a variety of tyrosine kinases. SH2B1 and SH2B2 function in signaling pathways found downstream of growth hormone receptor and receptor tyrosine kinases, including the insulin, insulin-like growth factor-I (IGF-I), platelet-derived growth factor (PDGF), nerve growth factor, hepatocyte growth factor, and fibroblast growth factor receptors. SH2B2beta, a new isoform of SH2B2, is an endogenous inhibitor of SH2B1 and/or SH2B2 (SH2B2alpha), negatively regulating insulin signaling and/or JAK2-mediated cellular responses. 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 728050533 401 ELELSDYPWFHGTLSRVKAAQLVLAGGPRSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHVQHLWFQSVF 480
Cdd:cd10410    2 DQPLSGYPWFHGMLSRLKAAQLVLEGGTGSHGVFLVRQSETRRGEYVLTFNFQGKAKHLRLSLNEEGQCRVQHLWFQSIF 81

                         90
                 ....*....|....*.
gi 728050533 481 DMLRHFHTHPIPLESG 496
Cdd:cd10410   82 DMLEHFRVHPIPLESG 97

Phenylalanine zipper; The phenylalanine zipper consists of aromatic side chains from ten phenylalanine residues that are stacked within a hydrophobic core. This zipper mediates dimerization of various proteins, such as APS and SH2-B/Lnk.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 728050533   17 DWRQFCELHAQVAAVDFAHKFCRFLRDNPTYDTPDAGTSFSRHFAANFLAVFSEEVR 73
Cdd:pfam08916   1 GWKEFCELHARAAASDFARAFRRFVRENPQYAAPLAHRDFSRKFAELFLEHFESEVK 57

Src homology 2 (SH2) domain; In general, SH2 domains are involved in signal transduction; they bind pTyr-containing polypeptide ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites. They are present in a wide array of proteins including: adaptor proteins (Nck1, Crk, Grb2), scaffolds (Slp76, Shc, Dapp1), kinases (Src, Syk, Fps, Tec), phosphatases (Shp-1, Shp-2), transcription factors (STAT1), Ras signaling molecules (Ras-Gap), ubiquitination factors (c-Cbl), cytoskeleton regulators (Tensin), signal regulators (SAP), and phospholipid second messengers (PLCgamma), amongst others.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 728050533 408 PWFHGTLSRVKAAQLvLAGGPrsHGLFVIRQSETRPGECVLTFNFQ-GKAKHLRLSLNGHGQCHV--QHLWFQSVFDMLR 484
Cdd:cd00173    1 PWFHGSISREEAERL-LRGKP--DGTFLVRESSSEPGDYVLSVRSGdGKVKHYLIERNEGGYYLLggSGRTFPSLPELVE 77

                 ..
gi 728050533 485 HF 486
Cdd:cd00173   78 HY 79

SH2 domain;

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|..
gi 728050533  409 WFHGTLSRVKAAQLVLAGGPrsHGLFVIRQSETRPGECVLTFNFQGKAKHLR 460
Cdd:pfam00017   1 WYHGKISRQEAERLLLNGKP--DGTFLVRESESTPGGYTLSVRDDGKVKHYK 50

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        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 728050533 401 ELELSDYPWFHGTLSRvKAAQLVLaggpRSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLsLNGHGQCHVQHLWFQSVF 480
Cdd:cd09925    1 AEQLRGEPWYHGKMSR-RDAESLL----QTDGDFLVRESTTTPGQYVLTGMQNGQPKHLLL-VDPEGVVRTKDRVFESIS 74

                         90       100
                 ....*....|....*....|....*...
gi 728050533 481 DMLRHFHTHPIPLESGGSADITLRSYVR 508
Cdd:cd09925   75 HLINYHVTNGLPIISEGSELHLRRPVRR 102

Src homology 2 (SH2) domain in the Breast Cancer Anti-estrogen Resistance protein 3; BCAR3 is part of a growing family of guanine nucleotide exchange factors is responsible for activation of Ras-family GTPases, including Sos1 and 2, GRF1 and 2, CalDAG-GEF/GRP1-4, C3G, cAMP-GEF/Epac 1 and 2, PDZ-GEFs, MR-GEF, RalGDS family members, RalGPS, RasGEF, Smg GDS, and phospholipase C(epsilon). 12102558 21262352 BCAR3 binds to the carboxy-terminus of BCAR1/p130Cas, a focal adhesion adapter protein. Over expression of BCAR1 (p130Cas) and BCAR3 induces estrogen independent growth in normally estrogen-dependent cell lines. They have been linked to resistance to anti-estrogens in breast cancer, Rac activation, and cell motility, though the BCAR3/p130Cas complex is not required for this activity in BCAR3. Many BCAR3-mediated signaling events in epithelial and mesenchymal cells are independent of p130Cas association. Structurally these proteins contain a single SH2 domain upstream of their RasGEF domain, which is responsible for the ability of BCAR3 to enhance p130Cas over-expression-induced migration. 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 728050533 403 ELSDYPWFHGTLSRVKAAQLVlaggpRSHGLFVIRQSETRPGECVLTFNFQGKAKHL---RLSLN-GHGQCHVQHLW--- 475
Cdd:cd10337    2 DLRSHAWYHGRIPRQVAESLV-----QREGDFLVRDSLSSPGDYVLTCRWKGQPLHFkinRVVLRpSEAYTRVQYQFede 76

                         90       100
                 ....*....|....*....|....
gi 728050533 476 -FQSVFDMLRHFHTH--PIPLESG 496
Cdd:cd10337   77 qFDSIPALVHFYVGNrrPISQASG 100

Src homology 2 (SH2) domain found in Abelson murine lymphosarcoma virus (ABL) proteins; ABL-family proteins are highly conserved tyrosine kinases. Each ABL protein contains an SH3-SH2-TK (Src homology 3-Src homology 2-tyrosine kinase) domain cassette, which confers autoregulated kinase activity and is common among nonreceptor tyrosine kinases. Several types of posttranslational modifications control ABL catalytic activity, subcellular localization, and stability, with consequences for both cytoplasmic and nuclear ABL functions. Binding partners provide additional regulation of ABL catalytic activity, substrate specificity, and downstream signaling. By combining this cassette with actin-binding and -bundling domain, ABL proteins are capable of connecting phosphoregulation with actin-filament reorganization. Vertebrate paralogs, ABL1 and ABL2, have evolved to perform specialized functions. ABL1 includes nuclear localization signals and a DNA binding domain which is used to mediate DNA damage-repair functions, while ABL2 has additional binding capacity for actin and for microtubules to enhance its cytoskeletal remodeling functions. SH2 is involved in several autoinhibitory mechanism that constrain the enzymatic activity of the ABL-family kinases. In one mechanism SH2 and SH3 cradle the kinase domain while a cap sequence stabilizes the inactive conformation resulting in a locked inactive state. Another involves phosphatidylinositol 4,5-bisphosphate (PIP2) which binds the SH2 domain through residues normally required for phosphotyrosine binding in the linker segment between the SH2 and kinase domains. The SH2 domain contributes to ABL catalytic activity and target site specificity. It is thought that the ABL catalytic site and SH2 pocket have coevolved to recognize the same sequences. Recent work now supports a hierarchical processivity model in which the substrate target site most compatible with ABL kinase domain preferences is phosphorylated with greatest efficiency. If this site is compatible with the ABL SH2 domain specificity, it will then reposition and dock in the SH2 pocket. This mechanism also explains how ABL kinases phosphorylates poor targets on the same substrate if they are properly positioned and how relatively poor substrate proteins might be recruited to ABL through a complex with strong substrates that can also dock with the SH2 pocket. 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 728050533 407 YPWFHGTLSRvKAAQLVLAGGprSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHV-QHLWFQSVFDMLRH 485
Cdd:cd09935    3 HSWYHGPISR-NAAEYLLSSG--INGSFLVRESESSPGQYSISLRYDGRVYHYRISEDSDGKVYVtQEHRFNTLAELVHH 79

                 ....*
gi 728050533 486 FHTHP 490
Cdd:cd09935   80 HSKNA 84

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        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 728050533 408 PWFHGTLSRVKAAQLVLAGGPRshGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHVQHLWFQSVFDMLRHF 486
Cdd:cd10354    1 IWFHGKISREEAYNMLVKVGGP--GSFLVRESDNTPGDYSLSFRVNEGIKHFKIIPTGNNQFMMGGRYFSSLDDVIDRY 77

Src homology 2 (SH2) domain found in the growth factor receptor bound, subclass 7 (Grb7) proteins; The Grb family binds to the epidermal growth factor receptor (EGFR, erbB1) via their SH2 domains. There are 3 members of the Grb7 family of proteins: Grb7, Grb10, and Grb14. They are composed of an N-terminal Proline-rich domain, a Ras Associating-like (RA) domain, a Pleckstrin Homology (PH) domain, a phosphotyrosine interaction region (PIR, BPS) and a C-terminal SH2 domain. The SH2 domains of Grb7, Grb10 and Grb14 preferentially bind to a different RTK. Grb7 binds strongly to the erbB2 receptor, unlike Grb10 and Grb14 which bind weakly to it. Grb14 binds to Fibroblast Growth Factor Receptor (FGFR). Grb10 has been shown to interact with many different proteins, including the insulin and IGF1 receptors, platelet-derived growth factor (PDGF) receptor-beta, Ret, Kit, Raf1 and MEK1, and Nedd4. Grb7 family proteins are phosphorylated on serine/threonine as well as tyrosine residues. 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
                 ....*....|....*....|....*....|....*....|....*....|.
gi 728050533 408 PWFHGTLSRVKAAQLVLAGGPRShGLFVIRQSETRPGECVLTFNFQGKAKH 458
Cdd:cd09944    6 PWFHGGISRDEAARLIRQQGLVD-GVFLVRESQSNPGAFVLSLKHGQKIKH 55

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 728050533 408 PWFHGTLSRVKAAQLvLAGGPRShGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHVQHLwFQSVFDMLRHFH 487
Cdd:cd09932    5 EWFHANLTREQAEEM-LMRVPRD-GAFLVRPSETDPNSFAISFRAEGKIKHCRIKQEGRLFVIGTSQ-FESLVELVSYYE 81

                 ...
gi 728050533 488 THP 490
Cdd:cd09932   82 KHP 84

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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 728050533 408 PWFHGTLSRVKAAQLVLAGGprSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHVQHLwFQSVFDMLRHFH 487
Cdd:cd09943    2 PWYYGRITRHQAETLLNEHG--HEGDFLIRDSESNPGDYSVSLKAPGRNKHFKVQVVDNVYCIGQRK-FHTMDELVEHYK 78

                 ....
gi 728050533 488 THPI 491
Cdd:cd09943   79 KAPI 82

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.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 728050533 410 FHGTLSRVKAAQLVLAGgprSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCH-VQHLWFQSVFDM----LR 484
Cdd:cd10352    9 YHGLISREEAEQLLSGA---SDGSYLIRESSRDDGYYTLSLRFNGKVKNYKLYYDGKNHYHyVGEKRFDTIHDLvadgLI 85

                 ...
gi 728050533 485 HFH 487
Cdd:cd10352   86 TLY 88

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.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 728050533 409 WFHGTLSRVKAAQLVLAGGPRShGLFVIRQSETRPGECVLTFNFQGKAKHLRLSlnghgqcHVQHLWF 476
Cdd:cd10348    2 WLHGALDRNEAVEILKQKADAD-GSFLVRYSRRRPGGYVLTLVYENHVYHFEIQ-------NRDDKWF 61

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 728050533 408 PWFHGTLSRVKAAqlvLAGGPRSH-GLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHVQHLwFQSVFDMLRHF 486
Cdd:cd10408    2 PWYYGKVTRHQAE---MALNERGNeGDFLIRDSESSPNDFSVSLKAQGKNKHFKVQLKECVYCIGQRK-FSSMEELVEHY 77

                 ....*
gi 728050533 487 HTHPI 491
Cdd:cd10408   78 KKAPI 82

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
                 ....*....|....*....|....*....|....*....|..
gi 728050533 408 PWFHGTLSRVKAAQLVLAGGpRSHGLFVIRQSETRPGECVLT 449
Cdd:cd09933    4 EWFFGKIKRKDAEKLLLAPG-NPRGTFLIRESETTPGAYSLS 44

Pleckstrin homology (PH) domain; PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 728050533 189 REGALRFMvaddaasGPGGTAQWQKCRLLLRRavagerFRLEFFVPPKA--SRPKVSIPLSAIIEVRTTMPlemPEKDNT 266
Cdd:cd00821    1 KEGYLLKR-------GGGGLKSWKKRWFVLFE------GVLLYYKSKKDssYKPKGSIPLSGILEVEEVSP---KERPHC 64

                         90       100
                 ....*....|....*....|....*...
gi 728050533 267 FVLKVENGAEYILETIDSLQKHSWVADI 294
Cdd:cd00821   65 FELVTPDGRTYYLQADSEEERQEWLKAL 92

Src homology 2 (SH2) domain found in the Src oncogene at 42A (Src42); Src42 is a member of the Src non-receptor type tyrosine kinase family of proteins. The integration of receptor tyrosine kinase-induced RAS and Src42 signals by Connector eNhancer of KSR (CNK) as a two-component input is essential for RAF activation in Drosophila. Src42 is present in a wide variety of organisms including: California sea hare, pea aphid, yellow fever mosquito, honey bee, Panamanian leafcutter ant, and sea urchin. Src42 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. 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. 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 728050533 408 PWFHGTLSRVKAAQLVLAGGpRSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHV-QHLWFQSVFDMLRHF 486
Cdd:cd10370    4 PWYFGKIKRIEAEKKLLLPE-NEHGAFLIRDSESRHNDYSLSVRDGDTVKHYRIRQLDEGGFFIaRRTTFRTLQELVEHY 82

Src homology 2 (SH2) domain in lymphocyte cell kinase (Lck); Lck is a member of the Src non-receptor type tyrosine kinase family of proteins. It is expressed in the brain, T-cells, and NK cells. The unique domain of Lck mediates its interaction with two T-cell surface molecules, CD4 and CD8. It associates with their cytoplasmic tails on CD4 T helper cells and CD8 cytotoxic T cells to assist signaling from the T cell receptor (TCR) complex. When the T cell receptor is engaged by the specific antigen presented by MHC, Lck phosphorylase the intracellular chains of the CD3 and zeta-chains of the TCR complex, allowing ZAP-70 to bind them. Lck then phosphorylates and activates ZAP-70, which in turn phosphorylates Linker of Activated T cells (LAT), a transmembrane protein that serves as a docking site for proteins including: Shc-Grb2-SOS, PI3K, and phospholipase C (PLC). The tyrosine phosphorylation cascade culminates in the intracellular mobilization of a calcium ions and activation of important signaling cascades within the lymphocyte, including the Ras-MEK-ERK pathway, which goes on to activate certain transcription factors such as NFAT, NF-kappaB, and AP-1. These transcription factors regulate the production cytokines such as Interleukin-2 that promote long-term proliferation and differentiation of the activated lymphocytes. The N-terminal tail of Lck is myristoylated and palmitoylated and it tethers the protein to the plasma membrane of the cell. Lck also contains a SH3 domain, a SH2 domain, and a C-terminal tyrosine kinase domain. Lck has 2 phosphorylation sites, the first an autophosphorylation site that is linked to activation of the protein and the second which is phosphorylated by Csk, which inhibits it. Lck is also inhibited by SHP-1 dephosphorylation and by Cbl ubiquitin ligase, which is part of the ubiquitin-mediated pathway. 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 728050533 408 PWFHGTLSRVKAAQLVLAGGpRSHGLFVIRQSETRPGECVLTF-NF---QGKA-KHLRL-SLNGHGQCHVQHLWFQSVFD 481
Cdd:cd10362    4 PWFFKNLSRNDAERQLLAPG-NTHGSFLIRESETTAGSFSLSVrDFdqnQGEVvKHYKIrNLDNGGFYISPRITFPGLHE 82

                 ....*
gi 728050533 482 MLRHF 486
Cdd:cd10362   83 LVRHY 87

Src homology 2 (SH2) domain found in SH2-containing inositol-5'-phosphatase (SHIP) and SLAM-associated protein (SAP); The SH2-containing inositol-5'-phosphatase, SHIP (also called SHIP1/SHIP1a), is a hematopoietic-restricted phosphatidylinositide phosphatase that translocates to the plasma membrane after extracellular stimulation and hydrolyzes the phosphatidylinositol-3-kinase (PI3K)-generated second messenger PI-3,4,5-P3 (PIP3) to PI-3,4-P2. As a result, SHIP dampens down PIP3 mediated signaling and represses the proliferation, differentiation, survival, activation, and migration of hematopoietic cells. PIP3 recruits lipid-binding pleckstrin homology(PH) domain-containing proteins to the inner wall of the plasma membrane and activates them. PH domain-containing downstream effectors include the survival/proliferation enhancing serine/threonine kinase, Akt (protein kinase B), the tyrosine kinase, Btk, the regulator of protein translation, S6K, and the Rac and cdc42 guanine nucleotide exchange factor, Vav. SHIP is believed to act as a tumor suppressor during leukemogenesis and lymphomagenesis, and may play a role in activating the immune system to combat cancer. SHIP contains an N-terminal SH2 domain, a centrally located phosphatase domain that specifically hydrolyzes the 5'-phosphate from PIP3, PI-4,5-P2 and inositol-1,3,4,5- tetrakisphosphate (IP4), a C2 domain, that is an allosteric activating site when bound by SHIP's enzymatic product, PI-3,4-P2; 2 NPXY motifs that bind proteins with a phosphotyrosine binding (Shc, Dok 1, Dok 2) or an SH2 (p85a, SHIP2) domain; and a proline-rich domain consisting of four PxxP motifs that bind a subset of SH3-containing proteins including Grb2, Src, Lyn, Hck, Abl, PLCg1, and PIAS1. The SH2 domain of SHIP binds to the tyrosine phosphorylated forms of Shc, SHP-2, Doks, Gabs, CD150, platelet-endothelial cell adhesion molecule, Cas, c-Cbl, immunoreceptor tyrosine-based inhibitory motifs (ITIMs), and immunoreceptor tyrosine-based activation motifs (ITAMs). The X-linked lymphoproliferative syndrome (XLP) gene encodes SAP (also called SH2D1A/DSHP) a protein that consists of a 5 residue N-terminus, a single SH2 domain, and a short 25 residue C-terminal tail. XLP is characterized by an extreme sensitivity to Epstein-Barr virus. Both T and natural killer (NK) cell dysfunctions have been seen in XLP patients. SAP binds the cytoplasmic tail of Signaling lymphocytic activation molecule (SLAM), 2B4, Ly-9, and CD84. SAP is believed to function as a signaling inhibitor, by blocking or regulating binding of other signaling proteins. SAP and the SAP-like protein EAT-2 recognize the sequence motif TIpYXX(V/I), which is found in the cytoplasmic domains of a restricted number of T, B, and NK cell surface receptors and are proposed to be natural inhibitors or regulators of the physiological role of a small family of receptors on the surface of these 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 728050533 405 SDYPWFHGTLSRVKAAQLVLAGGprSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHVQ 472
Cdd:cd10343    1 MAPPWYHGNITRSKAEELLSKAG--KDGSFLVRDSESVSGAYALCVLYQNCVHTYRILPNAEDKLSVQ 66

Src homology 2 (SH2) domain found in the Vav family; Vav proteins are involved in several processes that require cytoskeletal reorganization, such as the formation of the immunological synapse (IS), phagocytosis, platelet aggregation, spreading, and transformation. Vavs function as guanine nucleotide exchange factors (GEFs) for the Rho/Rac family of GTPases. Vav family members have several conserved motifs/domains including: a leucine-rich region, a leucine-zipper, a calponin homology (CH) domain, an acidic domain, a Dbl-homology (DH) domain, a pleckstrin homology (PH) domain, a cysteine-rich domain, 2 SH3 domains, a proline-rich region, and a SH2 domain. Vavs are the only known Rho GEFs that have both the DH/PH motifs and SH2/SH3 domains in the same protein. The leucine-rich helix-loop-helix (HLH) domain is thought to be involved in protein heterodimerization with other HLH proteins and it may function as a negative regulator by forming inactive heterodimers. The CH domain is usually involved in the association with filamentous actin, but in Vav it controls NFAT stimulation, Ca2+ mobilization, and its transforming activity. Acidic domains are involved in protein-protein interactions and contain regulatory tyrosines. The DH domain is a GDP-GTP exchange factor on Rho/Rac GTPases. The PH domain in involved in interactions with GTP-binding proteins, lipids and/or phosphorylated serine/threonine residues. The SH3 domain is involved in localization of proteins to specific sites within the cell interacting with protein with proline-rich sequences. The SH2 domain mediates a high affinity interaction with tyrosine phosphorylated proteins. There are three Vav mammalian family members: Vav1 which is expressed in the hematopoietic system, Vav2 and Vav3 are more ubiquitously expressed. The members here include insect and amphibian Vavs. 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
                 ....*....|....*....|....*....|....*....|....*....|....*...
gi 728050533 403 ELSDYPWFHGTLSRVKAAQLvLAGgpRSHGLFVIRQSETRPGECVLTFNFQGKAKHLR 460
Cdd:cd09940    1 DLSEFLWFVGEMERDTAENR-LEN--RPDGTYLVRVRPQGETQYALSIKYNGDVKHMK 55

Src homology 2 (SH2) domain found in SLAM-associated protein (SAP)1; The X-linked lymphoproliferative syndrome (XLP) gene encodes SAP (also called SH2D1A/DSHP) a protein that consists of a 5 residue N-terminus, a single SH2 domain, and a short 25 residue C-terminal tail. XLP is characterized by an extreme sensitivity to Epstein-Barr virus. Both T and natural killer (NK) cell dysfunctions have been seen in XLP patients. SAP binds the cytoplasmic tail of Signaling lymphocytic activation molecule (SLAM), 2B4, Ly-9, and CD84. SAP is believed to function as a signaling inhibitor, by blocking or regulating binding of other signaling proteins. SAP and the SAP-like protein EAT-2 recognize the sequence motif TIpYXX[VI], which is found in the cytoplasmic domains of a restricted number of T, B, and NK cell surface receptors and are proposed to be natural inhibitors or regulators of the physiological role of a small family of receptors on the surface of these 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 728050533 406 DYPWFHGTLSRVKAAQLVLAGGprSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNGHGQCHVQ 472
Cdd:cd10342    2 AVAVYHGKISRETGEKLLLATG--LDGSYLLRDSESVPGVYCLCVLYHGYIYTYRVSQTETGSWSAE 66

C-terminal Src homology 2 (SH2) domain found in Spleen tyrosine kinase (Syk) proteins; ZAP-70 and Syk comprise a family of hematopoietic cell specific protein tyrosine kinases (PTKs) that are required for antigen and antibody receptor function. ZAP-70 is expressed in T and natural killer (NK) cells and Syk is expressed in B cells, mast cells, polymorphonuclear leukocytes, platelets, macrophages, and immature T cells. They are required for the proper development of T and B cells, immune receptors, and activating NK cells. They consist of two N-terminal Src homology 2 (SH2) domains and a C-terminal kinase domain separated from the SH2 domains by a linker or hinge region. Phosphorylation of both tyrosine residues within the Immunoreceptor Tyrosine-based Activation Motifs (ITAM; consensus sequence Yxx[LI]x(7,8)Yxx[LI]) by the Src-family PTKs is required for efficient interaction of ZAP-70 and Syk with the receptor subunits and for receptor function. ZAP-70 forms two phosphotyrosine binding pockets, one of which is shared by both SH2 domains. In Syk the two SH2 domains do not form such a phosphotyrosine-binding site. The SH2 domains here are believed to function independently. In addition, the two SH2 domains of Syk display flexibility in their relative orientation, allowing Syk to accommodate a greater variety of spacing sequences between the ITAM phosphotyrosines and singly phosphorylated non-classical ITAM ligands. This model contains the C-terminus SH2 domains of Syk. 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 728050533 408 PWFHGTLSRVKAAQLVLAGGpRSHGLFVIRQSETRpGECVLTFNFQGKAKHLRLSLNGHGQCHV-QHLWFQSVFDMLRHF 486
Cdd:cd10401    4 PWFHGKISREESEQILLIGS-KTNGKFLIRERDNN-GSYALCLLHDGKVLHYRIDKDKTGKLSIpDGKKFDTLWQLVEHY 81

                 ....
gi 728050533 487 HTHP 490
Cdd:cd10401   82 SYKP 85

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 728050533 409 WFHGTLSRvKAAQLVLAGGPRshGLFVIRQSETRPGEcVLTFNFQGKAKHLRLSLNGHGQCHV--QHLWFQSVFDMLRHF 486
Cdd:cd09946    9 WFHGAISR-EAAENMLESQPL--GSFLIRVSHSHVGY-TLSYKAQSSCRHFMVKLLDDGTFMIpgEKVAHTSLHALVTFH 84

                 ....*
gi 728050533 487 HTHPI 491
Cdd:cd09946   85 QQKPI 89

Src homology 2 (SH2) domain found in the growth factor receptor bound, subclass 7 (Grb7) proteins; The Grb family binds to the epidermal growth factor receptor (EGFR, erbB1) via their SH2 domains. Grb7 is part of the Grb7 family of proteins which also includes Grb10, and Grb14. They are composed of an N-terminal Proline-rich domain, a Ras Associating-like (RA) domain, a Pleckstrin Homology (PH) domain, a phosphotyrosine interaction region (PIR, BPS) and a C-terminal SH2 domain. The SH2 domains of Grb7, Grb10 and Grb14 preferentially bind to a different RTK. Grb7 binds strongly to the erbB2 receptor, unlike Grb10 and Grb14 which bind weakly to it. Grb7 family proteins are phosphorylated on serine/threonine as well as tyrosine residues. 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
                 ....*....|....*....|....*....|....*....|....*....|.
gi 728050533 408 PWFHGTLSRVKAAQLVLAGGpRSHGLFVIRQSETRPGECVLTFNFQGKAKH 458
Cdd:cd10413    6 PWFHGRISREESQRLIGQQG-LVDGVFLVRESQRNPQGFVLSLCHLQKVKH 55

Src homology 2 domain found in cancer-related signaling adaptor protein CRK; SH2 domain in the CRK proteins. CRKI (SH2-SH3) and CRKII (SH2-SH3-SH3) are splicing isoforms of the oncoprotein CRK. CRKs regulate transcription and cytoskeletal reorganization for cell growth and motility by linking tyrosine kinases to small G proteins. The SH2 domain of CRK associates with tyrosine-phosphorylated receptors or components of focal adhesions, such as p130Cas and paxillin. CRK transmits signals to small G proteins through effectors that bind its SH3 domain, such as C3G, the guanine-nucleotide exchange factor (GEF) for Rap1 and R-Ras, and DOCK180, the GEF for Rac6. The binding of p130Cas to the CRK-C3G complex activates Rap1, leading to regulation of cell adhesion, and activates R-Ras, leading to JNK-mediated activation of cell proliferation, whereas the binding of CRK DOCK180 induces Rac1-mediated activation of cellular migration. The activity of the different splicing isoforms varies greatly with CRKI displaying substantial transforming activity, CRKII less so, and phosphorylated CRKII with no biological activity whatsoever. CRKII has a linker region with a phosphorylated Tyr and an additional C-terminal SH3 domain. The phosphorylated Tyr creates a binding site for its SH2 domain which disrupts the association between CRK and its SH2 target 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.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 728050533 409 WFHGTLSRvKAAQLVLAGgpRSHGLFVIRQSETRPGECVLTFNFQGKAKH 458
Cdd:cd09926    9 WYFGPMSR-QEAQELLQG--QRHGVFLVRDSSTIPGDYVLSVSENSRVSH 55

N-terminal Src homology 2 (N-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): [IVL]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.

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gi 728050533 409 WFHGTLSRVKAAQLVLAGGprSHGLFVIRQSETRPGECVLTFNFQGKAKHLRLSLNG 465
Cdd:cd10340    2 WFHPVISGIEAENLLKTRG--VDGSFLARPSKSNPGDFTLSVRRGDEVTHIKIQNTG 56

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 728050533 404 LSDYPWFHGTLSRVKAAQLVLAGGprSHGLFVIRQSETrPGecVLTFNFQGKA------KHLRLSLNGHGQCHV--QHLw 475
Cdd:cd09934    3 LEKYEWYVGDMSRQRAESLLKQED--KEGCFVVRNSST-KG--LYTVSLFTKVpgsphvKHYHIKQNARSEFYLaeKHC- 76

                         90
                 ....*....|....
gi 728050533 476 FQSVFDMLrHFHTH 489
Cdd:cd09934   77 FETIPELI-NYHQH 89