Collybistin/APC-stimulated guanine nucleotide exchange factor pleckstrin homology (PH) domain; Collybistin (also called PEM2) is homologous to the Dbl proteins ASEF (also called ARHGEF4/RhoGEF4) and SPATA13 (Spermatogenesis-associated protein 13; also called ASEF2). It activates CDC42 specifically and not any other Rho-family GTPases. Collybistin consists of an SH3 domain, followed by a RhoGEF/DH and PH domain. In Dbl proteins, the DH and PH domains catalyze the exchange of GDP for GTP in Rho GTPases, allowing them to signal to downstream effectors. It induces submembrane clustering of the receptor-associated peripheral membrane protein gephyrin, which is thought to form a scaffold underneath the postsynaptic membrane linking receptors to the cytoskeleton. It also acts as a tumor suppressor that links adenomatous polyposis coli (APC) protein, a negative regulator of the Wnt signaling pathway and promotes the phosphorylation and degradation of beta-catenin, to Cdc42. Autoinhibition of collybistin is accomplished by the binding of its SH3 domain with both the RhoGEF and PH domains to block access of Cdc42 to the GTPase-binding site. Inactivation promotes cancer progression. 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 594150350 270 LENIDKIAQWQASVLDWEGEDILDRSSELIYTGEMAWIYqpYGRNQQRVFFLFDHQMVLCKKDLIRRDILYYKGRIDMDK 349
Cdd:cd01224    1 MENLEKLAAWQSTVEGWEGEDLSDRSSELIHSGELTKIS--AGRAQERTFFLFDHQLVYCKKDLLRRKNYIYKGRIDTDN 78

                         90       100       110       120       130       140
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350 350 YEVIDIEDGRDDDFNVSMKNAFKLHNKETEEVHLFFAKKLEEKIRWLRAFREERKMVQED 409
Cdd:cd01224   79 MEIEDLPDGKDDESGVTVKNAWKIYNASKNKWYVLCAKSAEEKQRWLEAFAEEREKVEKD 138

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

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*..
gi 594150350   1 MANRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRLWVNQ 47
Cdd:cd11975   16 MANRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRLWVNQ 62

Collybistin/APC-stimulated guanine nucleotide exchange factor pleckstrin homology (PH) domain; Collybistin (also called PEM2) is homologous to the Dbl proteins ASEF (also called ARHGEF4/RhoGEF4) and SPATA13 (Spermatogenesis-associated protein 13; also called ASEF2). It activates CDC42 specifically and not any other Rho-family GTPases. Collybistin consists of an SH3 domain, followed by a RhoGEF/DH and PH domain. In Dbl proteins, the DH and PH domains catalyze the exchange of GDP for GTP in Rho GTPases, allowing them to signal to downstream effectors. It induces submembrane clustering of the receptor-associated peripheral membrane protein gephyrin, which is thought to form a scaffold underneath the postsynaptic membrane linking receptors to the cytoskeleton. It also acts as a tumor suppressor that links adenomatous polyposis coli (APC) protein, a negative regulator of the Wnt signaling pathway and promotes the phosphorylation and degradation of beta-catenin, to Cdc42. Autoinhibition of collybistin is accomplished by the binding of its SH3 domain with both the RhoGEF and PH domains to block access of Cdc42 to the GTPase-binding site. Inactivation promotes cancer progression. 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 594150350 270 LENIDKIAQWQASVLDWEGEDILDRSSELIYTGEMAWIYqpYGRNQQRVFFLFDHQMVLCKKDLIRRDILYYKGRIDMDK 349
Cdd:cd01224    1 MENLEKLAAWQSTVEGWEGEDLSDRSSELIHSGELTKIS--AGRAQERTFFLFDHQLVYCKKDLLRRKNYIYKGRIDTDN 78

                         90       100       110       120       130       140
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350 350 YEVIDIEDGRDDDFNVSMKNAFKLHNKETEEVHLFFAKKLEEKIRWLRAFREERKMVQED 409
Cdd:cd01224   79 MEIEDLPDGKDDESGVTVKNAWKIYNASKNKWYVLCAKSAEEKQRWLEAFAEEREKVEKD 138

Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases; Also called Dbl-homologous (DH) domain. It appears that PH domains invariably occur C-terminal to RhoGEF/DH domains.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350  83 RANVINEIMSTERHYIKHLKDICEGYLKQCRKRRDMFSDEQLKVIFGNIEDIYRFQMGFVRDLEKQYNNDDPHLSEIGPC 162
Cdd:cd00160    1 RQEVIKELLQTERNYVRDLKLLVEVFLKPLDKELLPLSPEEVELLFGNIEEIYEFHRIFLKSLEERVEEWDKSGPRIGDV 80

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350 163 FLEHQDGFWIYSEYCNNHLDACMELSKLMKDSryqHFFEACRLLQQ--MIDIAIDGFLLTPVQKICKYPLQLAELLKYTA 240
Cdd:cd00160   81 FLKLAPFFKIYSEYCSNHPDALELLKKLKKFN---KFFQEFLEKAEseCGRLKLESLLLKPVQRLTKYPLLLKELLKHTP 157

                        170       180
                 ....*....|....*....|....
gi 594150350 241 QDHSDYRYVAAALAVMRNVTQQIN 264
Cdd:cd00160  158 DGHEDREDLKKALEAIKEVASQVN 181

Src homology 3 domain of the Rho guanine nucleotide exchange factor ARHGEF9; ARHGEF9, also called PEM2 or collybistin, selectively activates Cdc42 by exchanging bound GDP for free GTP. It is highly expressed in the brain and it interacts with gephyrin, a postsynaptic protein associated with GABA and glycine receptors. Mutations in the ARHGEF9 gene cause X-linked mental retardation with associated features like seizures, hyper-anxiety, aggressive behavior, and sensory hyperarousal. ARHGEF9 contains a SH3 domain followed by RhoGEF (also called Dbl-homologous or DH) and Pleckstrin Homology (PH) domains. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*..
gi 594150350   1 MANRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRLWVNQ 47
Cdd:cd11975   16 MANRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRLWVNQ 62

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 594150350   298 LIYTGEMAWIYQPYGRN-QQRVFFLFDHQMVLCKKDLIRRDILYyKGRIDMDKYEVIDIEDGRDDDfnvsMKNAFKLHNK 376
Cdd:smart00233   1 VIKEGWLYKKSGGGKKSwKKRYFVLFNSTLLYYKSKKDKKSYKP-KGSIDLSGCTVREAPDPDSSK----KPHCFEIKTS 75

                           90       100
                   ....*....|....*....|....*
gi 594150350   377 eTEEVHLFFAKKLEEKIRWLRAFRE 401
Cdd:smart00233  76 -DRKTLLLQAESEEEREKWVEALRK 99

RhoGEF, Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases [Signal transduction mechanisms];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350   74 RPLQNRDQMRANVINEIMSTERHYIKHLKDICEGYLKQC--------RKRRDMfsdeqLKVIFGNIEDIYRFQMGFVRDL 145
Cdd:COG5422   476 ESLPKQEIKRQEAIYEVIYTERDFVKDLEYLRDTWIKPLeesniipeNARRNF-----IKHVFANINEIYAVNSKLLKAL 550

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350  146 EKQyNNDDPHLSEIGPCFLEHQDGFWIYSEYCNNHLDACMEL----SKLMKDSRYQHFFEACRLLQQMidiAIDGFLLTP 221
Cdd:COG5422   551 TNR-QCLSPIVNGIADIFLDYVPKFEPFIKYGASQPYAKYEFerekSVNPNFARFDHEVERLDESRKL---ELDGYLTKP 626

                         170       180       190       200
                  ....*....|....*....|....*....|....*....|...
gi 594150350  222 VQKICKYPLQLAELLKYTAQDHSDYRYVAAALAVMRNVTQQIN 264
Cdd:COG5422   627 TTRLARYPLLLEEVLKFTDPDNPDTEDIPKVIDMLREFLSRLN 669

Collybistin/APC-stimulated guanine nucleotide exchange factor pleckstrin homology (PH) domain; Collybistin (also called PEM2) is homologous to the Dbl proteins ASEF (also called ARHGEF4/RhoGEF4) and SPATA13 (Spermatogenesis-associated protein 13; also called ASEF2). It activates CDC42 specifically and not any other Rho-family GTPases. Collybistin consists of an SH3 domain, followed by a RhoGEF/DH and PH domain. In Dbl proteins, the DH and PH domains catalyze the exchange of GDP for GTP in Rho GTPases, allowing them to signal to downstream effectors. It induces submembrane clustering of the receptor-associated peripheral membrane protein gephyrin, which is thought to form a scaffold underneath the postsynaptic membrane linking receptors to the cytoskeleton. It also acts as a tumor suppressor that links adenomatous polyposis coli (APC) protein, a negative regulator of the Wnt signaling pathway and promotes the phosphorylation and degradation of beta-catenin, to Cdc42. Autoinhibition of collybistin is accomplished by the binding of its SH3 domain with both the RhoGEF and PH domains to block access of Cdc42 to the GTPase-binding site. Inactivation promotes cancer progression. 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 594150350 270 LENIDKIAQWQASVLDWEGEDILDRSSELIYTGEMAWIYqpYGRNQQRVFFLFDHQMVLCKKDLIRRDILYYKGRIDMDK 349
Cdd:cd01224    1 MENLEKLAAWQSTVEGWEGEDLSDRSSELIHSGELTKIS--AGRAQERTFFLFDHQLVYCKKDLLRRKNYIYKGRIDTDN 78

                         90       100       110       120       130       140
                 ....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350 350 YEVIDIEDGRDDDFNVSMKNAFKLHNKETEEVHLFFAKKLEEKIRWLRAFREERKMVQED 409
Cdd:cd01224   79 MEIEDLPDGKDDESGVTVKNAWKIYNASKNKWYVLCAKSAEEKQRWLEAFAEEREKVEKD 138

Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases; Also called Dbl-homologous (DH) domain. It appears that PH domains invariably occur C-terminal to RhoGEF/DH domains.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350  83 RANVINEIMSTERHYIKHLKDICEGYLKQCRKRRDMFSDEQLKVIFGNIEDIYRFQMGFVRDLEKQYNNDDPHLSEIGPC 162
Cdd:cd00160    1 RQEVIKELLQTERNYVRDLKLLVEVFLKPLDKELLPLSPEEVELLFGNIEEIYEFHRIFLKSLEERVEEWDKSGPRIGDV 80

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350 163 FLEHQDGFWIYSEYCNNHLDACMELSKLMKDSryqHFFEACRLLQQ--MIDIAIDGFLLTPVQKICKYPLQLAELLKYTA 240
Cdd:cd00160   81 FLKLAPFFKIYSEYCSNHPDALELLKKLKKFN---KFFQEFLEKAEseCGRLKLESLLLKPVQRLTKYPLLLKELLKHTP 157

                        170       180
                 ....*....|....*....|....
gi 594150350 241 QDHSDYRYVAAALAVMRNVTQQIN 264
Cdd:cd00160  158 DGHEDREDLKKALEAIKEVASQVN 181

Src homology 3 domain of the Rho guanine nucleotide exchange factor ARHGEF9; ARHGEF9, also called PEM2 or collybistin, selectively activates Cdc42 by exchanging bound GDP for free GTP. It is highly expressed in the brain and it interacts with gephyrin, a postsynaptic protein associated with GABA and glycine receptors. Mutations in the ARHGEF9 gene cause X-linked mental retardation with associated features like seizures, hyper-anxiety, aggressive behavior, and sensory hyperarousal. ARHGEF9 contains a SH3 domain followed by RhoGEF (also called Dbl-homologous or DH) and Pleckstrin Homology (PH) domains. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*..
gi 594150350   1 MANRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRLWVNQ 47
Cdd:cd11975   16 MANRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRLWVNQ 62

Src homology 3 domain of APC-Stimulated guanine nucleotide Exchange Factor 2; ASEF2, also called Spermatogenesis-associated protein 13 (SPATA13), is a GEF that localizes with actin at the leading edge of cells and is important in cell migration and adhesion dynamics. GEFs activate small GTPases by exchanging bound GDP for free GTP. ASEF2 can activate both Rac 1 and Cdc42, but only Rac1 activation is necessary for increased cell migration and adhesion turnover. Together with APC (adenomatous polyposis coli) and Neurabin2, a scaffold protein that binds F-actin, it is involved in regulating HGF-induced cell migration. ASEF2 contains a SH3 domain followed by RhoGEF (also called Dbl-homologous or DH) and Pleckstrin Homology (PH) domains. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|...
gi 594150350   1 MANRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRL 43
Cdd:cd11974   12 MDDQELAFKAGDVIRVLEASNKDWWWGRNEDREAWFPASFVRL 54

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

                           10        20        30
                   ....*....|....*....|....*....|....*....
gi 594150350     5 ELAFKAGDVIKVLDASNKDWWWGQIDD-EEGWFPASFVR 42
Cdd:smart00326  18 ELSFKKGDIITVLEKSDDGWWKGRLGRgKEGLFPSNYVE 56

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

                         10        20        30
                 ....*....|....*....|....*....|....*..
gi 594150350   5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd11805   15 ELEFRRGDIITVLDSSDPDWWKGELRGRVGIFPANYV 51

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

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|
gi 594150350   3 NRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVR 42
Cdd:cd11856   13 DDEISLQEGEVVEVLEKNDSGWWYVRKGDKEGWVPASYLE 52

Src homology 3 domain of Growth Arrest Specific protein 7; GAS7 is mainly expressed in the brain and is required for neurite outgrowth. It may also play a role in the protection and migration of embryonic stem cells. Treatment-related acute myeloid leukemia (AML) has been reported resulting from mixed-lineage leukemia (MLL)-GAS7 translocations as a complication of primary cancer treatment. GAS7 contains an N-terminal SH3 domain, followed by a WW domain, and a central F-BAR domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*.
gi 594150350   6 LAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd11829   17 LSFEAGELIRVLQAPDGGWWEGEKDGLRGWFPASYV 52

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

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|
gi 594150350   3 NRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVR 42
Cdd:cd11985   13 NNDLPLQPGDRVMVVDDSNEDWWKGKSGDRVGFFPANFVQ 52

Src homology 3 domain of Signal Transducing Adaptor Molecules; STAMs were discovered as proteins that are highly phosphorylated following cytokine and growth factor stimulation. They function in cytokine signaling and surface receptor degradation, as well as regulate Golgi morphology. They associate with many proteins including Jak2 and Jak3 tyrosine kinases, Hrs, AMSH, and UBPY. STAM adaptor proteins contain VHS (Vps27, Hrs, STAM homology), ubiquitin interacting (UIM), and SH3 domains. There are two vertebrate STAMs, STAM1 and STAM2, which may be functionally redundant; vertebrate STAMs contain ITAM motifs. They are part of the endosomal sorting complex required for transport (ESCRT-0). STAM2 deficiency in mice did not cause any obvious abnormality, while STAM1 deficiency resulted in growth retardation. Loss of both STAM1 and STAM2 in mice proved lethal, indicating that STAMs are important for embryonic development. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*..
gi 594150350   5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd11820   16 ELTFKAGEIITVLDDSDPNWWKGSNHRGEGLFPANFV 52

Son of Sevenless (SOS) Pleckstrin homology (PH) domain; SOS is a Ras guanine nucleotide exchange factor. SOS is thought to transmit signals from activated receptor tyrosine kinases to the Ras signaling pathway. SOS contains a histone domain, Dbl-homology (DH), a PH domain, Rem domain, Cdc25 domain, and a Grb2 binding domain. The SOS PH domain binds to phosphatidylinositol-4,5-bisphosphate (PIP2) and phosphatidic acid (PA). SOS is dependent on Ras binding to the allosteric site via its histone domain for both a lower level of activity (Ras GDP) and maximal activity (Ras GTP). The DH domain blocks the allosteric Ras binding site in SOS. The PH domain is closely associated with the DH domain and the action of the DH-PH unit gates a reciprocal interaction between Ras and SOS. The C-terminal proline-rich domain of SOS binds to the adapter protein Grb2 which localizes the Sos protein to the plasma membrane and diminishes the negative effect of the C-terminal domain on the guanine nucleotide exchange activity of the CDC25-homology domain of SOS. 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 594150350 295 SSELIYTGEMAwIYQPYGRNQQRVFFLFDHQMVLCKKDLIRR------DILYYKGRIDMDKYEVIDIEDGRDddfnvsMK 368
Cdd:cd01261    3 CNEFIMEGTLG-KVGSGKRKTERHAFLFDGLLLLCKSNRRRTstggpkPEYRLKEKFFIRKVEINDLEDTEE------LK 75

                         90       100       110
                 ....*....|....*....|....*....|.
gi 594150350 369 NAFKLHNKETEEVhLFFAKKLEEKIRWLRAF 399
Cdd:cd01261   76 NAFEIVPRDQPSV-ILFAKSAEEKNNWMAAL 105

Third Src homology 3 domain of Tyrosine kinase substrate (Tks) proteins; Tks proteins are Src substrates and scaffolding proteins that play important roles in the formation of podosomes and invadopodia, the dynamic actin-rich structures that are related to cell migration and cancer cell invasion. Vertebrates contain two Tks proteins, Tks4 (Tyr kinase substrate with four SH3 domains) and Tks5 (Tyr kinase substrate with five SH3 domains), which display partially overlapping but non-redundant functions. Both associate with the ADAMs family of transmembrane metalloproteases, which function as sheddases and mediators of cell and matrix interactions. Tks5 interacts with N-WASP and Nck, while Tks4 is essential for the localization of MT1-MMP (membrane-type 1 matrix metalloproteinase) to invadopodia. Tks proteins contain an N-terminal Phox homology (PX) domain and four or five SH3 domains. This model characterizes the third SH3 domain of Tks proteins. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*.
gi 594150350   6 LAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd12017   16 ISFQKGQKVEVIDKNPSGWWYVKIDGKEGWAPSSYI 51

First Src homology 3 domain of Tyrosine kinase substrate with five SH3 domains; Tks5, also called SH3 and PX domain-containing protein 2A (SH3PXD2A) or Five SH (FISH), is a scaffolding protein and Src substrate that is localized in podosomes, which are electron-dense structures found in Src-transformed fibroblasts, osteoclasts, macrophages, and some invasive cancer cells. It binds and regulates some members of the ADAMs family of transmembrane metalloproteases, which function as sheddases and mediators of cell and matrix interactions. It is required for podosome formation, degradation of the extracellular matrix, and cancer cell invasion. Tks5 contains an N-terminal Phox homology (PX) domain and five SH3 domains. This model characterizes the first SH3 domain of Tks5. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*....
gi 594150350   3 NRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd12074   13 NSEISLQAGEVVDVIEKNESGWWFVSTAEEQGWVPATYL 51

Src Homology 3 domain of the p40phox subunit of NADPH oxidase; p40phox, also called Neutrophil cytosol factor 4 (NCF-4), is a cytosolic subunit of the phagocytic NADPH oxidase complex (also called Nox2 or gp91phox) which plays a crucial role in the cellular response to bacterial infection. NADPH oxidase catalyzes the transfer of electrons from NADPH to oxygen during phagocytosis forming superoxide and reactive oxygen species. p40phox positively regulates NADPH oxidase in both phosphatidylinositol-3-phosphate (PI3P)-dependent and PI3P-independent manner. It contains an N-terminal PX domain, a central SH3 domain, and a C-terminal PB1 domain that interacts with p67phox. The SH3 domain of p40phox binds to canonical polyproline and noncanonical motifs at the C-terminus of p47phox. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*....
gi 594150350   5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRL 43
Cdd:cd11869   15 ELNFKAGDVIFLLSRVNKDWLEGTVRGATGIFPLSFVKI 53

Src homology 3 domain of Protein arginine N-methyltransferase 2; PRMT2, also called HRMT1L1, belongs to the arginine methyltransferase protein family. It functions as a coactivator to both estrogen receptor alpha (ER-alpha) and androgen receptor (AR), presumably through arginine methylation. The ER-alpha transcription factor is involved in cell proliferation, differentiation, morphogenesis, and apoptosis, and is also implicated in the development and progression of breast cancer. PRMT2 and its variants are upregulated in breast cancer cells and may be involved in modulating the ER-alpha signaling pathway during formation of breast cancer. PRMT2 also plays a role in regulating the function of E2F transcription factors, which are critical cell cycle regulators, by binding to the retinoblastoma gene product (RB). It contains an N-terminal SH3 domain and an AdoMet binding domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*....
gi 594150350   3 NRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd11806   13 DSQLSFESGDKLLVLRKPSVDWWWAEHNGCCGYIPASHL 51

Pleckstrin homology domain-containing family G members 1, 2, and 3 pleckstrin homology (PH) domain; PLEKHG1 (also called ARHGEF41), PLEKHG2 (also called ARHGEF42 or CLG/common-site lymphoma/leukemia guanine nucleotide exchange factor2), and PLEKHG3 (also called ARHGEF43) have RhoGEF DH/double-homology domains in tandem with a PH domain which is involved in phospholipid binding. They function as a guanine nucleotide exchange factor (GEF) and are involved in the regulation of Rho protein signal transduction. Mutations in PLEKHG1 have been associated panic disorder (PD), an anxiety disorder characterized by panic attacks and anticipatory anxiety. 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 594150350 249 VAAALAVMRNVTQQINERKRRLENIDKIAQWQASVLDWEGEDILDRSSELIYTGemawiYQPYGRNQQRVFFLFDHQMVL 328
Cdd:cd13243    4 VEEALDTMTQVAWHINDMKRKHEHAVRVQEIQSLLDGWEGPELTTYGDLVLEGT-----FRMAGAKNERLLFLFDKMLLI 78

                         90       100       110       120       130       140       150
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 594150350 329 CKKdliRRDILY-YKGRIDMDKYEVIDIEDGRDDDFNVsmknafkLHNKETEEVHLFFAKKLEEKIRWLRAFR 400
Cdd:cd13243   79 TKK---REDGILqYKTHIMCSNLMLSESIPKEPLSFQV-------LPFDNPKLQYTLQAKNQEQKRLWTQEIK 141

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

                         10        20        30
                 ....*....|....*....|....*....|....*...
gi 594150350   5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVR 42
Cdd:cd12046   15 DLEFQKGDVILVLSKVNEDWLEGQCKGKIGIFPSAFVE 52

RhoGEF, Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases [Signal transduction mechanisms];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350   74 RPLQNRDQMRANVINEIMSTERHYIKHLKDICEGYLKQC--------RKRRDMfsdeqLKVIFGNIEDIYRFQMGFVRDL 145
Cdd:COG5422   476 ESLPKQEIKRQEAIYEVIYTERDFVKDLEYLRDTWIKPLeesniipeNARRNF-----IKHVFANINEIYAVNSKLLKAL 550

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350  146 EKQyNNDDPHLSEIGPCFLEHQDGFWIYSEYCNNHLDACMEL----SKLMKDSRYQHFFEACRLLQQMidiAIDGFLLTP 221
Cdd:COG5422   551 TNR-QCLSPIVNGIADIFLDYVPKFEPFIKYGASQPYAKYEFerekSVNPNFARFDHEVERLDESRKL---ELDGYLTKP 626

                         170       180       190       200
                  ....*....|....*....|....*....|....*....|...
gi 594150350  222 VQKICKYPLQLAELLKYTAQDHSDYRYVAAALAVMRNVTQQIN 264
Cdd:COG5422   627 TTRLARYPLLLEEVLKFTDPDNPDTEDIPKVIDMLREFLSRLN 669

First Src homology 3 domain of Tyrosine kinase substrate (Tks) proteins; Tks proteins are Src substrates and scaffolding proteins that play important roles in the formation of podosomes and invadopodia, the dynamic actin-rich structures that are related to cell migration and cancer cell invasion. Vertebrates contain two Tks proteins, Tks4 (Tyr kinase substrate with four SH3 domains) and Tks5 (Tyr kinase substrate with five SH3 domains), which display partially overlapping but non-redundant functions. Both associate with the ADAMs family of transmembrane metalloproteases, which function as sheddases and mediators of cell and matrix interactions. Tks5 interacts with N-WASP and Nck, while Tks4 is essential for the localization of MT1-MMP (membrane-type 1 matrix metalloproteinase) to invadopodia. Tks proteins contain an N-terminal Phox homology (PX) domain and four or five SH3 domains. This model characterizes the first SH3 domain of Tks proteins. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*...
gi 594150350   3 NRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASF 40
Cdd:cd12015   13 PNEISLRAGDVVDVIEKNENGWWFVSLEDEQGWVPATY 50

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

                         10        20        30
                 ....*....|....*....|....*....|....*..
gi 594150350   5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd11951   15 QLSFRRGDIIEVLDCPDPNWWRGRISGRVGFFPRNYV 51

Src Homology 3 domain of Apoptosis Stimulating of p53 protein 1; ASPP1, like ASPP2, activates the apoptotic function of the p53 family of tumor suppressors (p53, p63, and p73). In addition, it functions in the cytoplasm to regulate the nuclear localization of the transcriptional cofactors YAP and TAZ by inihibiting their phosphorylation; YAP and TAZ are important regulators of cell expansion, differentiation, migration, and invasion. ASPP1 is downregulated in breast tumors expressing wild-type p53. It contains a proline-rich region, four ankyrin (ANK) repeats, and an SH3 domain at its C-terminal half. The SH3 domain and the ANK repeats of ASPP1 contribute to the p53 binding site; they bind to the DNA binding domain of p53. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|..
gi 594150350   5 ELAFKAGDVIKVL---DASNKDWWWGQIDDEEGWFPASFVRL 43
Cdd:cd11954   16 ELSFQEGDAITILrrkDDSETEWWWARLNDKEGYVPKNLLGL 57

Src Homology 3 domain of Pak Interactive eXchange factors; PIX proteins are Rho guanine nucleotide exchange factors (GEFs), which activate small GTPases by exchanging bound GDP for free GTP. They act as GEFs for both Cdc42 and Rac 1, and have been implicated in cell motility, adhesion, neurite outgrowth, and cell polarity. Vertebrates contain two proteins from the PIX subfamily, alpha-PIX and beta-PIX. Alpha-PIX, also called ARHGEF6, is localized in dendritic spines where it regulates spine morphogenesis. Mutations in the ARHGEF6 gene cause X-linked intellectual disability in humans. Beta-PIX play roles in regulating neuroendocrine exocytosis, focal adhesion maturation, cell migration, synaptic vesicle localization, and insulin secretion. PIX proteins contain an N-terminal SH3 domain followed by RhoGEF (also called Dbl-homologous or DH) and Pleckstrin Homology (PH) domains, and a C-terminal leucine-zipper domain for dimerization. The SH3 domain of PIX binds to an atypical PxxxPR motif in p21-activated kinases (PAKs) with high affinity. The binding of PAKs to PIX facilitate the localization of PAKs to focal complexes and also localizes PAKs to PIX targets Cdc43 and Rac, leading to the activation of PAKs. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|.
gi 594150350   3 NRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRL 43
Cdd:cd11877   13 EDELSFDKGDIITVTQVVEGGWWEGTLNGKTGWFPSNYVKE 53

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

                         10        20        30
                 ....*....|....*....|....*....|....*....
gi 594150350   5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRL 43
Cdd:cd11874   15 ELELKVGDTIEVLGEVEEGWWEGKLNGKVGVFPSNFVKE 53

Third Src homology 3 domain of Tyrosine kinase substrate with four SH3 domains; Tks4, also called SH3 and PX domain-containing protein 2B (SH3PXD2B) or HOFI, is a Src substrate and scaffolding protein that plays an important role in the formation of podosomes and invadopodia, the dynamic actin-rich structures that are related to cell migration and cancer cell invasion. It is required in the formation of functional podosomes, EGF-induced membrane ruffling, and lamellipodia generation. It plays an important role in cellular attachment and cell spreading. Tks4 is essential for the localization of MT1-MMP (membrane-type 1 matrix metalloproteinase) to invadopodia. It contains an N-terminal Phox homology (PX) domain and four SH3 domains. This model characterizes the third SH3 domain of Tks4. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*.
gi 594150350   6 LAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd12078   16 ISFQAGLKVEVIEKNLSGWWYIQIEDKEGWAPATFI 51

C-terminal Src homology 3 domain of Growth factor receptor-bound protein 2; GRB2 is a critical signaling molecule that regulates the Ras pathway by linking tyrosine kinases to the Ras guanine nucleotide releasing protein Sos (son of sevenless), which converts Ras to the active GTP-bound state. It is ubiquitously expressed in all tissues throughout development and is important in cell cycle progression, motility, morphogenesis, and angiogenesis. In lymphocytes, GRB2 is associated with antigen receptor signaling components. GRB2 contains an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. The C-terminal SH3 domain of GRB2 binds to Gab2 (Grb2-associated binder 2) through epitopes containing RxxK motifs, as well as to the proline-rich C-terminus of FGRF2. SH3 domains are protein interaction domains that typically bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*...
gi 594150350   5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVR 42
Cdd:cd11949   15 ELGFRRGDFIEVMDNSDPNWWKGACHGQTGMFPRNYVT 52

Vav pleckstrin homology (PH) domain; Vav acts as a guanosine nucleotide exchange factor (GEF) for Rho/Rac proteins. They control processes including T cell activation, phagocytosis, and migration of cells. The Vav subgroup of Dbl GEFs consists of three family members (Vav1, Vav2, and Vav3) in mammals. Vav1 is preferentially expressed in the hematopoietic system, while Vav2 and Vav3 are described by broader expression patterns. Mammalian Vav proteins consist of a calponin homology (CH) domain, an acidic region, a catalytic Dbl homology (DH) domain, a PH domain, a zinc finger cysteine rich domain (C1/CRD), and an SH2 domain, flanked by two SH3 domains. In invertebrates such as Drosophila and C. elegans, Vav is missing the N-terminal SH3 domain. The DH domain is involved in RhoGTPase recognition and selectivity and stimulates the reorganization of the switch regions for GDP/GTP exchange. The PH domain is implicated in directing membrane localization, allosteric regulation of guanine nucleotide exchange activity, and as a phospholipid- dependent regulator of GEF activity. Vavs bind RhoGTPases including Rac1, RhoA, RhoG, and Cdc42, while other members of the GEF family are specific for a single RhoGTPase. This promiscuity is thought to be a result of its CRD. 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.polarized. PH domains also have diverse functions. They are often involved in targeting proteins to the plasma membrane, but only a few (less than 10%) display strong specificity in binding inositol phosphates. 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 kinases, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, cytoskeletal associated molecules, and in lipid associated enzymes.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350 315 QQRVFFLFDHQMVLCKKdlIRRDILYYKGRIDMDKYEVIDIEDGRDDDFNVSMKNAFKLHNKETEEVHLFFAKKLEEKIR 394
Cdd:cd01223   36 KDRYAFLFDKVLLICKS--LRGDQYEYKEIINLSEYRIEDDPSRRTLKRDKRWSYQFLLVHKQGKTAYTLYAKTEELKKK 113

                 ....*..
gi 594150350 395 WLRAFRE 401
Cdd:cd01223  114 WMEAIEM 120

PH domain; PH stands for pleckstrin homology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 594150350  315 QQRVFFLFDHQMVLCKKDLIRRDiLYYKGRIDMDKYEVIDIEDgrDDDFNVSMKNAFKLHNKETEEVHLFFAKKLEEKIR 394
Cdd:pfam00169  19 KKRYFVLFDGSLLYYKDDKSGKS-KEPKGSISLSGCEVVEVVA--SDSPKRKFCFELRTGERTGKRTYLLQAESEEERKD 95

                  ....*..
gi 594150350  395 WLRAFRE 401
Cdd:pfam00169  96 WIKAIQS 102

Second Src homology 3 domain (or SH3B) of Intersectin-2; Intersectin-2 (ITSN2) is an adaptor protein that functions in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. It plays a role in clathrin-coated pit (CCP) formation. It binds to many proteins through its multidomain structure and facilitate the assembly of multimeric complexes. ITSN2 also functions as a specific GEF for Cdc42 activation in epithelial morphogenesis, and is required in mitotic spindle orientation. It exists in alternatively spliced short and long isoforms. The short isoform contains two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoform, in addition, contains RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. The second SH3 domain (or SH3B) of ITSN2 is expected to bind protein partners, similar to ITSN1 which has been shown to bind WNK and CdGAP. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|.
gi 594150350   3 NRELAFKAGDVIKVLDaSNKDWWWGQIDDEEGWFPASFVRL 43
Cdd:cd11990   13 DNHLNFSKNDIITVLE-QQENWWFGEVHGGRGWFPKSYVKL 52

Third Src homology 3 domain of Tyrosine kinase substrate with five SH3 domains; Tks5, also called SH3 and PX domain-containing protein 2A (SH3PXD2A) or Five SH (FISH), is a scaffolding protein and Src substrate that is localized in podosomes, which are electron-dense structures found in Src-transformed fibroblasts, osteoclasts, macrophages, and some invasive cancer cells. It binds and regulates some members of the ADAMs family of transmembrane metalloproteases, which function as sheddases and mediators of cell and matrix interactions. It is required for podosome formation, degradation of the extracellular matrix, and cancer cell invasion. Tks5 contains an N-terminal Phox homology (PX) domain and five SH3 domains. This model characterizes the third SH3 domain of Tks5. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*.
gi 594150350   6 LAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd12079   17 ISFRGGQKAEVIEKNSGGWWYVQIGEKEGWAPSSYI 52

Src homology 3 domain of Myosins Ie, If, and similar proteins; Myosins Ie (MyoIe) and If (MyoIf) are nonmuscle, unconventional, long tailed, class I myosins containing an N-terminal motor domain and a myosin tail with TH1, TH2, and SH3 domains. MyoIe interacts with the endocytic proteins, dynamin and synaptojanin-1, through its SH3 domain; it may play a role in clathrin-dependent endocytosis. In the kidney, MyoIe is critical for podocyte function and normal glomerular filtration. Mutations in MyoIe is associated with focal segmental glomerulosclerosis, a disease characterized by massive proteinuria and progression to end-stage kidney disease. MyoIf is predominantly expressed in the immune system; it plays a role in immune cell motility and innate immunity. Mutations in MyoIf may be associated with the loss of hearing. The MyoIf gene has also been found to be fused to the MLL (Mixed lineage leukemia) gene in infant acute myeloid leukemias (AML). SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30
                 ....*....|....*....|....*....|....*..
gi 594150350   5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd11827   15 ELSFNEGDIIEILKEDPSGWWTGRLRGKEGLFPGNYV 51

Src Homology 3 domain of Myosin XV; This subfamily is composed of proteins with similarity to Myosin XVa. Myosin XVa is an unconventional myosin that is critical for the normal growth of mechanosensory stereocilia of inner ear hair cells. Mutations in the myosin XVa gene are associated with nonsyndromic hearing loss. Myosin XVa contains a unique N-terminal extension followed by a motor domain, light chain-binding IQ motifs, and a tail consisting of a pair of MyTH4-FERM tandems separated by a SH3 domain, and a PDZ domain. SH3 domains bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs; they play a role in the regulation of enzymes by intramolecular interactions, changing the subcellular localization of signal pathway components and mediate multiprotein complex assemblies.

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gi 594150350   6 LAFKAGDVIKVLDAS---NKDWWWGQIDDEEGWFPASFV 41
Cdd:cd11884   16 LSFHKGDVIKLLPKEgplDPGWLFGTLDGRSGAFPKEYV 54

Src Homology 3 domain of Small G protein Signaling Modulator 3; SGSM3 is also called Merlin-associated protein (MAP), RUN and SH3 domain-containing protein (RUSC3), RUN and TBC1 domain-containing protein 3 (RUTBC3), Rab GTPase-activating protein 5 (RabGAP5), or Rab GAP-like protein (RabGAPLP). It is expressed ubiquitously and functions as a regulator of small G protein RAP- and RAB-mediated neuronal signaling. It is involved in modulating NGF-mediated neurite outgrowth and differentiation. It also interacts with the tumor suppressor merlin and may play a role in the merlin-associated suppression of cell growth. SGSM3 contains TBC, SH3, and RUN domains. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 594150350   5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVRL 43
Cdd:cd11813   15 ELGFRKNDIITIISQKDEHCWVGELNGLRGWFPAKFVEL 53

Variant SH3 domain;

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gi 594150350    5 ELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFVR 42
Cdd:pfam14604  12 ELSLQRGDVITVIEESEDGWWEGINTGRTGLVPANYVE 49

Third N-terminal Src homology 3 domain of Dynamin Binding Protein, also called Tuba; DNMBP or Tuba is a cdc42-specific guanine nucleotide exchange factor (GEF) that contains four N-terminal SH3 domains, a central RhoGEF [or Dbl homology (DH)] domain followed by a Bin/Amphiphysin/Rvs (BAR) domain, and two C-terminal SH3 domains. It provides a functional link between dynamin and key regulatory proteins of the actin cytoskeleton. It plays an important role in regulating cell junction configuration. The four N-terminal SH3 domains of DNMBP binds the GTPase dynamin, which plays an important role in the fission of endocytic vesicles. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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                 ....*....|....*....|....*....|....*....
gi 594150350   3 NRELAFKAGDVIKVLDASNKDWWWGQIDDEEGWFPASFV 41
Cdd:cd11796   13 DEELDLREGDVVTITGILDKGWFRGELNGRRGIFPEGFV 51