Ephexin Pleckstrin homology (PH) domain; Ephexin-1 (also called NGEF/ neuronal guanine nucleotide exchange factor) plays a role in the homeostatic modulation of presynaptic neurotransmitter release. Specific functions are still unknown for Ephexin-2 (also called RhoGEF19) and Ephexin-3 (also called Rho guanine nucleotide exchange factor 5/RhoGEF5, Transforming immortalized mammary oncogene/p60 TIM, and NGEF/neuronalGEF). Ephexin-4 (also called RhoGEF16) acts downstream of EphA2 to promote ligand-independent breast cancer cell migration and invasion toward epidermal growth factor through activation of RhoG. This in turn results in the activation of RhoG which recruits ELMO2 and Dock4 to form a complex with EphA2 at the tips of cortactin-rich protrusions in migrating breast cancer cells. Ephexin-5 is the specific GEF for RhoA activation and the regulation of vascular smooth muscle contractility. It interacts with EPHA4 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. The members of the Ephexin family contains a RhoGEF (DH) followed by a PH domain and an SH3 domain. The ephexin PH domain is believed to act with the DH domain in mediating protein-protein interactions. 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 189027103 489 KVKSLPLISASRWLLKR---GELLLLEESSIFRKIASRPTCYLFLFNDVLVVTKKKSEESYLVQDYAQLDHVQVRKVEPS 565
Cdd:cd01221    1 KIKAFPLISSSRWLVKRgelTELVEDGGSLTFRKKFSKTPVYLFLFNDLLLITKKKSEERYLVLDYAPRNLVQVEEVEDP 80

                         90       100       110       120       130
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 189027103 566 ELPLPGGssrsssVPYPFQVNLLHNSEGRQEQILLSSDSASDRARWITALSYKERQW 622
Cdd:cd01221   81 LQLPQPL------GKNLFLLTLLENHEGKTVELLLSAESESDRERWLSALSPPKSEL 131

Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases; 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. Improved coverage.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 189027103   288 AIFEILTSEFSYLHSLKILVNEFLQS-QELKTTMTQTEHHHLFSNISDVLAASQKFFESLEQRHKAQVC-VEDISDILED 365
Cdd:smart00325   1 VLKELLQTERNYVRDLKLLVEVFLKPlKKELKLLSPNELETLFGNIEEIYEFHRDFLDELEERIEEWDDsVERIGDVFLK 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 189027103   366 HAEnHFHPYIAYCSNEVYQQRTLQKLsNSNTAFREVLREIEKLPACGGLPMISFLILPMQRVTRLPLLTDTLCLKTQGHP 445
Cdd:smart00325  81 LEE-FFKIYSEYCSNHPDALELLKKL-KKNPRFQKFLKEIESSPQCRRLTLESLLLKPVQRLTKYPLLLKELLKHTPEDH 158

                          170       180
                   ....*....|....*....|..
gi 189027103   446 ERYKAASRALKAISKLVKQCNE 467
Cdd:smart00325 159 EDREDLKKALKAIKELANQVNE 180

Ephexin Pleckstrin homology (PH) domain; Ephexin-1 (also called NGEF/ neuronal guanine nucleotide exchange factor) plays a role in the homeostatic modulation of presynaptic neurotransmitter release. Specific functions are still unknown for Ephexin-2 (also called RhoGEF19) and Ephexin-3 (also called Rho guanine nucleotide exchange factor 5/RhoGEF5, Transforming immortalized mammary oncogene/p60 TIM, and NGEF/neuronalGEF). Ephexin-4 (also called RhoGEF16) acts downstream of EphA2 to promote ligand-independent breast cancer cell migration and invasion toward epidermal growth factor through activation of RhoG. This in turn results in the activation of RhoG which recruits ELMO2 and Dock4 to form a complex with EphA2 at the tips of cortactin-rich protrusions in migrating breast cancer cells. Ephexin-5 is the specific GEF for RhoA activation and the regulation of vascular smooth muscle contractility. It interacts with EPHA4 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. The members of the Ephexin family contains a RhoGEF (DH) followed by a PH domain and an SH3 domain. The ephexin PH domain is believed to act with the DH domain in mediating protein-protein interactions. 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 189027103 489 KVKSLPLISASRWLLKR---GELLLLEESSIFRKIASRPTCYLFLFNDVLVVTKKKSEESYLVQDYAQLDHVQVRKVEPS 565
Cdd:cd01221    1 KIKAFPLISSSRWLVKRgelTELVEDGGSLTFRKKFSKTPVYLFLFNDLLLITKKKSEERYLVLDYAPRNLVQVEEVEDP 80

                         90       100       110       120       130
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 189027103 566 ELPLPGGssrsssVPYPFQVNLLHNSEGRQEQILLSSDSASDRARWITALSYKERQW 622
Cdd:cd01221   81 LQLPQPL------GKNLFLLTLLENHEGKTVELLLSAESESDRERWLSALSPPKSEL 131

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

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 189027103  274 ILDTLSVEERKRQEAIFEILTSEFSYLHSLKILVNEFLQ----SQELKTTMTQTEHHHLFSNISDVLAASQKFFESLEQR 349
Cdd:COG5422   474 VWESLPKQEIKRQEAIYEVIYTERDFVKDLEYLRDTWIKpleeSNIIPENARRNFIKHVFANINEIYAVNSKLLKALTNR 553

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 189027103  350 HKAQVCVEDISDILEDHAEnHFHPYIAYCSNEVYQQRTLQKLSNSNTAFREVLREIEKLPACGGLPMISFLILPMQRVTR 429
Cdd:COG5422   554 QCLSPIVNGIADIFLDYVP-KFEPFIKYGASQPYAKYEFEREKSVNPNFARFDHEVERLDESRKLELDGYLTKPTTRLAR 632

                         170       180       190       200       210
                  ....*....|....*....|....*....|....*....|....*....|....*...
gi 189027103  430 LPLLTDTLCLKTQGHPERYKAASRALKAISKLVKQCNEGAHKMERTEQMYTLHMQLDF 487
Cdd:COG5422   633 YPLLLEEVLKFTDPDNPDTEDIPKVIDMLREFLSRLNFESGKAENRGDLFHLNQQLLF 690

Variant SH3 domain;

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 189027103  636 VTKAYFAKQADEITLQQADVVLVLQE-EDGWLYGErlRDGETGWFPESF 683
Cdd:pfam14604   1 ALYPYEPKDDDELSLQRGDVITVIEEsEDGWWEGI--NTGRTGLVPANY 47

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 189027103   526 CYLFLFNDVLVVTK-KKSEESYLVQDYAQLDHVQVRKVEPSElplpggssrSSSVPYPFQVNLlhnseGRQEQILLSSDS 604
Cdd:smart00233  21 RYFVLFNSTLLYYKsKKDKKSYKPKGSIDLSGCTVREAPDPD---------SSKKPHCFEIKT-----SDRKTLLLQAES 86

                           90
                   ....*....|.
gi 189027103   605 ASDRARWITAL 615
Cdd:smart00233  87 EEEREKWVEAL 97

Guanine nucleotide exchange factor for Rho/Rac/Cdc42-like GTPases; 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. Improved coverage.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 189027103   288 AIFEILTSEFSYLHSLKILVNEFLQS-QELKTTMTQTEHHHLFSNISDVLAASQKFFESLEQRHKAQVC-VEDISDILED 365
Cdd:smart00325   1 VLKELLQTERNYVRDLKLLVEVFLKPlKKELKLLSPNELETLFGNIEEIYEFHRDFLDELEERIEEWDDsVERIGDVFLK 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 189027103   366 HAEnHFHPYIAYCSNEVYQQRTLQKLsNSNTAFREVLREIEKLPACGGLPMISFLILPMQRVTRLPLLTDTLCLKTQGHP 445
Cdd:smart00325  81 LEE-FFKIYSEYCSNHPDALELLKKL-KKNPRFQKFLKEIESSPQCRRLTLESLLLKPVQRLTKYPLLLKELLKHTPEDH 158

                          170       180
                   ....*....|....*....|..
gi 189027103   446 ERYKAASRALKAISKLVKQCNE 467
Cdd:smart00325 159 EDREDLKKALKAIKELANQVNE 180

Ephexin Pleckstrin homology (PH) domain; Ephexin-1 (also called NGEF/ neuronal guanine nucleotide exchange factor) plays a role in the homeostatic modulation of presynaptic neurotransmitter release. Specific functions are still unknown for Ephexin-2 (also called RhoGEF19) and Ephexin-3 (also called Rho guanine nucleotide exchange factor 5/RhoGEF5, Transforming immortalized mammary oncogene/p60 TIM, and NGEF/neuronalGEF). Ephexin-4 (also called RhoGEF16) acts downstream of EphA2 to promote ligand-independent breast cancer cell migration and invasion toward epidermal growth factor through activation of RhoG. This in turn results in the activation of RhoG which recruits ELMO2 and Dock4 to form a complex with EphA2 at the tips of cortactin-rich protrusions in migrating breast cancer cells. Ephexin-5 is the specific GEF for RhoA activation and the regulation of vascular smooth muscle contractility. It interacts with EPHA4 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. The members of the Ephexin family contains a RhoGEF (DH) followed by a PH domain and an SH3 domain. The ephexin PH domain is believed to act with the DH domain in mediating protein-protein interactions. 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 189027103 489 KVKSLPLISASRWLLKR---GELLLLEESSIFRKIASRPTCYLFLFNDVLVVTKKKSEESYLVQDYAQLDHVQVRKVEPS 565
Cdd:cd01221    1 KIKAFPLISSSRWLVKRgelTELVEDGGSLTFRKKFSKTPVYLFLFNDLLLITKKKSEERYLVLDYAPRNLVQVEEVEDP 80

                         90       100       110       120       130
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 189027103 566 ELPLPGGssrsssVPYPFQVNLLHNSEGRQEQILLSSDSASDRARWITALSYKERQW 622
Cdd:cd01221   81 LQLPQPL------GKNLFLLTLLENHEGKTVELLLSAESESDRERWLSALSPPKSEL 131

Src homology 3 domain of ephexin-1-like SH3 domain containing Rho guanine nucleotide exchange factors; Members of this family contain RhoGEF (also called Dbl-homologous or DH), Pleckstrin Homology (PH), and C-terminal SH3 domains. They include the Rho guanine nucleotide exchange factors ARHGEF5, ARHGEF16, ARHGEF19, ARHGEF26, ARHGEF27 (also called ephexin-1), and similar proteins, and are also called ephexins because they interact directly with ephrin A receptors. GEFs interact with Rho GTPases via their DH domains to catalyze nucleotide exchange by stabilizing the nucleotide-free GTPase intermediate. They play important roles in neuronal development. The SH3 domains of ARHGEFs play an autoinhibitory role through intramolecular interactions with a proline-rich region N-terminal to the DH domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 189027103 633 QVEVTKAYFAKQADEITLQQADVVLVLQEE-DGWLYGERLRDGETGWFPESFA 684
Cdd:cd11793    1 QVQCVHAYTAQQPDELTLEEGDVVNVLRKMpDGWYEGERLRDGERGWFPSSYT 53

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

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 189027103  274 ILDTLSVEERKRQEAIFEILTSEFSYLHSLKILVNEFLQ----SQELKTTMTQTEHHHLFSNISDVLAASQKFFESLEQR 349
Cdd:COG5422   474 VWESLPKQEIKRQEAIYEVIYTERDFVKDLEYLRDTWIKpleeSNIIPENARRNFIKHVFANINEIYAVNSKLLKALTNR 553

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 189027103  350 HKAQVCVEDISDILEDHAEnHFHPYIAYCSNEVYQQRTLQKLSNSNTAFREVLREIEKLPACGGLPMISFLILPMQRVTR 429
Cdd:COG5422   554 QCLSPIVNGIADIFLDYVP-KFEPFIKYGASQPYAKYEFEREKSVNPNFARFDHEVERLDESRKLELDGYLTKPTTRLAR 632

                         170       180       190       200       210
                  ....*....|....*....|....*....|....*....|....*....|....*...
gi 189027103  430 LPLLTDTLCLKTQGHPERYKAASRALKAISKLVKQCNEGAHKMERTEQMYTLHMQLDF 487
Cdd:COG5422   633 YPLLLEEVLKFTDPDNPDTEDIPKVIDMLREFLSRLNFESGKAENRGDLFHLNQQLLF 690

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

                           10        20        30        40        50
                   ....*....|....*....|....*....|....*....|....*....|....*
gi 189027103   630 ELPQVEVTKAYFAKQADEITLQQADVVLVL-QEEDGWLYGeRLRDGETGWFPESF 683
Cdd:smart00326   1 EGPQVRALYDYTAQDPDELSFKKGDIITVLeKSDDGWWKG-RLGRGKEGLFPSNY 54

First Src homology 3 domain (or SH3A) of Intersectin; Intersectins (ITSNs) are adaptor proteins that function in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. They are essential for initiating clathrin-coated pit formation. They bind to many proteins through their multidomain structure and facilitate the assembly of multimeric complexes. Vertebrates contain two ITSN proteins, ITSN1 and ITSN2, which exist in alternatively spliced short and long isoforms. The short isoforms contain two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoforms, in addition, contain RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. ITSN1 and ITSN2 are both widely expressed, with variations depending on tissue type and stage of development. The first SH3 domain (or SH3A) of ITSN1 has been shown to bind many proteins including Sos1, dynamin1/2, CIN85, c-Cbl, PI3K-C2, SHIP2, N-WASP, and CdGAP, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*....
gi 189027103 639 AYFAKQADEITLQQADVVLVLQE---EDGWLYGErlRDGETGWFPESFA 684
Cdd:cd11836    7 AFEARNPDEISFQPGDIIQVDESqvaEPGWLAGE--LKGKTGWFPANYV 53

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

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|..
gi 189027103 640 YFAKQADEITLQQADVVLVLQEE-DGWLYGErlRDGETGWFP 680
Cdd:cd11766    8 YEAQREDELSLRKGDRVLVLEKSsDGWWRGE--CNGQVGWFP 47

Src Homology 3 domain of Insulin Receptor tyrosine kinase Substrate p53, Brain-specific Angiogenesis Inhibitor 1-Associated Protein 2 (BAIAP2)-Like proteins, and similar proteins; Proteins in this family include IRSp53, BAIAP2L1, BAIAP2L2, and similar proteins. They all contain an Inverse-Bin/Amphiphysin/Rvs (I-BAR) or IMD domain in addition to the SH3 domain. IRSp53, also known as BAIAP2, is a scaffolding protein that takes part in many signaling pathways including Cdc42-induced filopodia formation, Rac-mediated lamellipodia extension, and spine morphogenesis. IRSp53 exists as multiple splicing variants that differ mainly at the C-termini. BAIAP2L1, also called IRTKS (Insulin Receptor Tyrosine Kinase Substrate), serves as a substrate for the insulin receptor and binds the small GTPase Rac. It plays a role in regulating the actin cytoskeleton and colocalizes with F-actin, cortactin, VASP, and vinculin. IRSp53 and IRTKS also mediate the recruitment of effector proteins Tir and EspFu, which regulate host cell actin reorganization, to bacterial attachment sites. BAIAP2L2 co-localizes with clathrin plaques but its function has not been determined. The SH3 domains of IRSp53 and IRTKS have been shown to bind the proline-rich C-terminus of EspFu. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....
gi 189027103 632 PQVEVTKAYFAKQADEITLQQADVVLVL--QEEDGWLYGERLRDGETGWFPESF 683
Cdd:cd11779    1 PRVKALYPHAAGGETQLSFEEGDVITLLgpEPRDGWHYGENERSGRRGWFPIAY 54

Variant SH3 domain;

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*....
gi 189027103  636 VTKAYFAKQADEITLQQADVVLVLQE-EDGWLYGErlRDGETGWFPESF 683
Cdd:pfam14604   1 ALYPYEPKDDDELSLQRGDVITVIEEsEDGWWEGI--NTGRTGLVPANY 47

First Src homology 3 domain (or SH3A) of Intersectin-1; Intersectin-1 (ITSN1) is an adaptor protein that functions in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. It plays a role in clathrin-coated pit (CCP) formation. It binds to many proteins through its multidomain structure and facilitate the assembly of multimeric complexes. ITSN1 localizes in membranous organelles, CCPs, the Golgi complex, and may be involved in the cell membrane trafficking system. It exists in alternatively spliced short and long isoforms. The short isoform contains two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoform, in addition, contains RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. The first SH3 domain (or SH3A) of ITSN1 has been shown to bind many proteins including Sos1, dynamin1/2, CIN85, c-Cbl, PI3K-C2, SHIP2, N-WASP, and CdGAP, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*.
gi 189027103 642 AKQADEITLQQADVVLVLQE---EDGWLYGErlRDGETGWFPESFA 684
Cdd:cd11987   10 ARSHDEITIQPGDIVMVDESqtgEPGWLGGE--LKGKTGWFPANYA 53

Second Src Homology 3 domain of Bzz1 and similar domains; Bzz1 (or Bzz1p) is a WASP/Las17-interacting protein involved in endocytosis and trafficking to the vacuole. It physically interacts with type I myosins and functions in the early steps of endocytosis. Together with other proteins, it induces membrane scission in yeast. Bzz1 contains an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs), a central coiled-coil, and two C-terminal SH3 domains. This model represents the second C-terminal SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 189027103 634 VEVTKAYFAKQADEITLQQADVVLVLQEEDG--WLYGERlrDGETGWFPESF 683
Cdd:cd11778    2 VEALYDYEAQGDDEISIRVGDRIAVIRGDDGsgWTYGEI--NGVKGLFPTSY 51

PH domain; PH stands for pleckstrin homology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 189027103  526 CYLFLFNDVLVVTK-KKSEESYLVQDYAQLDHVQVRKVEPSElplpggssrSSSVPYPFQVNLLHNSEGRqeQILLSSDS 604
Cdd:pfam00169  21 RYFVLFDGSLLYYKdDKSGKSKEPKGSISLSGCEVVEVVASD---------SPKRKFCFELRTGERTGKR--TYLLQAES 89

                          90
                  ....*....|..
gi 189027103  605 ASDRARWITALS 616
Cdd:pfam00169  90 EEERKDWIKAIQ 101

Src Homology 3 domain of Class A Dedicator of Cytokinesis proteins 1 and 5; Dock1, also called Dock180, and Dock5 are class A DOCKs and are atypical guanine nucleotide exchange factors (GEFs) that lack the conventional Dbl homology (DH) domain. Dock1 interacts with the scaffold protein Elmo and the resulting complex functions upstream of Rac in many biological events including phagocytosis of apoptotic cells, cell migration and invasion. Dock5 functions upstream of Rac1 to regulate osteoclast function. All DOCKs contain two homology domains: the DHR-1 (Dock homology region-1), also called CZH1 (CED-5, Dock180, and MBC-zizimin homology 1), and DHR-2 (also called CZH2 or Docker). The DHR-1 domain binds phosphatidylinositol-3,4,5-triphosphate while DHR-2 contains the catalytic activity for Rac and/or Cdc42. Class A DOCKs also contain an SH3 domain at the N-terminal region and a PxxP motif at the C-terminus; they are specific GEFs for Rac. The SH3 domain of Dock1 binds to DHR-2 in an autoinhibitory manner; binding of Elmo to the SH3 domain of Dock1 exposes the DHR-2 domain and promotes GEF activity. 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 189027103 640 YFAKQADEITLQQADVVLVLQEEDGWLYGERLRD-GETGWFPESFAH 685
Cdd:cd12051    8 YDARGPDELSLQIGDTVHILETYEGWYRGYTLRKkSKKGIFPASYIH 54

Src homology 3 domain of Nitric Oxide Synthase TRaffic INducer; Nostrin is expressed in endothelial and epithelial cells and is involved in the regulation, trafficking and targeting of endothelial NOS (eNOS). It facilitates the endocytosis of eNOS by coordinating the functions of dynamin and the Wiskott-Aldrich syndrome protein (WASP). Increased expression of Nostrin may be correlated to preeclampsia. Nostrin contains an N-terminal F-BAR domain and a C-terminal SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*.
gi 189027103 639 AYFAKQADEITLQQADVVLVL-QEEDGWLYGErLRdGETGWFPESF 683
Cdd:cd11823    7 SYTANREDELSLQPGDIIEVHeKQDDGWWLGE-LN-GKKGIFPATY 50

C-terminal Src Homology 3 domain of Nebulin; Nebulin is a giant filamentous protein (600-900 kD) that is expressed abundantly in skeletal muscle. It binds to actin thin filaments and regulates its assembly and function. Nebulin was thought to be part of a molecular ruler complex that is critical in determining the lengths of actin thin filaments in skeletal muscle since its length, which varies due to alternative splicing, correlates with the length of thin filaments in various muscle types. Recent studies indicate that nebulin regulates thin filament length by stabilizing the filaments and preventing depolymerization. Mutations in nebulin can cause nemaline myopathy, characterized by muscle weakness which can be severe and can lead to neonatal lethality. Nebulin contains an N-terminal LIM domain, many nebulin repeats/super repeats, and a C-terminal SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*....
gi 189027103 640 YFAKQADEITLQQADVVLVLQE-EDGWLYGERLRDGETGWFPESFAHCI 687
Cdd:cd11933   10 YRAADDDEVSFKDGDTIVNVQTiDEGWMYGTVQRTGKTGMLPANYVEAI 58

Src Homology 3 domain of Sorting Nexin 9 and similar proteins; Sorting nexins (SNXs) are Phox homology (PX) domain containing proteins that are involved in regulating membrane traffic and protein sorting in the endosomal system. SNXs differ from each other in their lipid-binding specificity, subcellular localization and specific function in the endocytic pathway. This subfamily consists of SH3 domain containing SNXs including SNX9, SNX18, SNX33, and similar proteins. SNX9 is localized to plasma membrane endocytic sites and acts primarily in clathrin-mediated endocytosis, while SNX18 is localized to peripheral endosomal structures, and acts in a trafficking pathway that is clathrin-independent but relies on AP-1 and PACS1. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
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gi 189027103 633 QVEVTKAYFAKQADEITLQQADVVLVLQE--EDGWLYGERLRdGETGWFPESF 683
Cdd:cd11763    1 KVRALYDFDSQPSGELSLRAGEVLTITRQdvGDGWLEGRNSR-GEVGLFPSSY 52

Second Src homology 3 domain (or SH3B) of Intersectin-1; Intersectin-1 (ITSN1) is an adaptor protein that functions in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. It plays a role in clathrin-coated pit (CCP) formation. It binds to many proteins through its multidomain structure and facilitate the assembly of multimeric complexes. ITSN1 localizes in membranous organelles, CCPs, the Golgi complex, and may be involved in the cell membrane trafficking system. It exists in alternatively spliced short and long isoforms. The short isoform contains two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoform, in addition, contains RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. The second SH3 domain (or SH3B) of ITSN1 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        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 189027103 633 QVEVTKAYFAKQADEITLQQADVVLVLQEEDGWLYGErlRDGETGWFPESF 683
Cdd:cd11989    1 QAQALYPWRAKKDNHLNFNKNDVITVLEQQDMWWFGE--VQGQKGWFPKSY 49

C-terminal Src Homology 3 domain of the Nebulin family of proteins; Nebulin family proteins contain multiple nebulin repeats, and may contain an N-terminal LIM domain and/or a C-terminal SH3 domain. They have molecular weights ranging from 34 to 900 kD, depending on the number of nebulin repeats, and they all bind actin. They are involved in the regulation of actin filament architecture and function as stabilizers and scaffolds for cytoskeletal structures with which they associate, such as long actin filaments or focal adhesions. Nebulin family proteins that contain a C-terminal SH3 domain include the giant filamentous protein nebulin, nebulette, Lasp1, and Lasp2. Lasp2, also called LIM-nebulette, is an alternatively spliced variant of nebulette. 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
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gi 189027103 640 YFAKQADEITLQQADVVLVLQE-EDGWLYGERLRDGETGWFP 680
Cdd:cd11789    8 YAAADDDEVSFQEGDVIINVEIiDDGWMEGTVQRTGQSGMLP 49

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.

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gi 189027103 633 QVEVTKAYFAKQADEITLQQADVVLVLQE-EDGWLYGErlRDGETGWFPESF 683
Cdd:cd11856    1 SYVAIADYEAQGDDEISLQEGEVVEVLEKnDSGWWYVR--KGDKEGWVPASY 50

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
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gi 189027103 639 AYFAKQADEITLQQADVVLVLQEEDGWLYGErLRdGETGWFPESF 683
Cdd:cd11990    7 SWTAKKDNHLNFSKNDIITVLEQQENWWFGE-VH-GGRGWFPKSY 49

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.

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gi 189027103 635 EVTKAYFAKQADEITLQQADVVLVL-QEEDGWLYGErlRDGETGWFPESF 683
Cdd:cd11874    3 KVLFSYTPQNEDELELKVGDTIEVLgEVEEGWWEGK--LNGKVGVFPSNF 50

C-terminal Src Homology 3 domain of Nebulette and LIM-nebulette (or Lasp2); Nebulette is a cardiac-specific protein that localizes to the Z-disc. It interacts with tropomyosin and is important in stabilizing actin thin filaments in cardiac muscles. Polymorphisms in the nebulette gene are associated with dilated cardiomyopathy, with some mutations resulting in severe heart failure. Nebulette is a 107kD protein that contains an N-terminal acidic region, multiple nebulin repeats, and a C-terminal SH3 domain. LIM-nebulette, also called Lasp2 (LIM and SH3 domain protein 2), is an alternatively spliced variant of nebulette. Although it shares a gene with nebulette, Lasp2 is not transcribed from a muscle-specific promoter, giving rise to its multiple tissue expression pattern with highest amounts in the brain. It can crosslink actin filaments and it affects cell spreading. Lasp2 is a 34kD protein containing an N-terminal LIM domain, three nebulin repeats, and a C-terminal SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 189027103 640 YFAKQADEITLQQADVVLVLQE-EDGWLYGERLRDGETGWFPESF 683
Cdd:cd11935    9 YSAQDEDEVSFRDGDYIVNVQPiDEGWMYGTVQRTGRTGMLPANY 53

First Src homology 3 domain (or SH3A) 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 first SH3 domain (or SH3A) of ITSN2 is expected to bind many protein partners, similar to ITSN1 which has been shown to bind Sos1, dynamin1/2, CIN85, c-Cbl, PI3K-C2, SHIP2, N-WASP, and CdGAP, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 189027103 642 AKQADEITLQQADVVLVLQE---EDGWLYGERlrDGETGWFPESFA 684
Cdd:cd11988   12 ARNHDEMSFNAGDIIQVDEKtvgEPGWLYGSF--QGNFGWFPCNYV 55

Third Src Homology 3 domain of SH3 domain containing ring finger 1 (SH3RF1), SH3RF3, and similar domains; SH3RF1 (or POSH) and SH3RF3 (or POSH2) are scaffold proteins that function as E3 ubiquitin-protein ligases. They contain an N-terminal RING finger domain and four SH3 domains. This model represents the third SH3 domain, located in the middle of SH3RF1 and SH3RF3, and similar domains. SH3RF1 plays a role in calcium homeostasis through the control of the ubiquitin domain protein Herp. It may also have a role in regulating death receptor mediated and JNK mediated apoptosis. SH3RF3 interacts with p21-activated kinase 2 (PAK2) and GTP-loaded Rac1. It may play a role in regulating JNK mediated apoptosis in certain conditions. 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
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gi 189027103 639 AYFAKQADEITLQQADVVLVLQE-EDGWLYGERLRDGETGWFP 680
Cdd:cd11783    7 PYKPQKPDELELRKGEMYTVTEKcQDGWFKGTSLRTGQSGVFP 49

Third Src Homology 3 domain of SH3 domain containing ring finger 2; SH3RF2 is also called POSHER (POSH-eliminating RING protein) or HEPP1 (heart protein phosphatase 1-binding protein). It acts as an anti-apoptotic regulator of the JNK pathway by binding to and promoting the degradation of SH3RF1 (or POSH), a scaffold protein that is required for pro-apoptotic JNK activation. It may also play a role in cardiac functions together with protein phosphatase 1. SH3RF2 contains an N-terminal RING finger domain and three SH3 domains. This model represents the third SH3 domain, located in the middle, of SH3RF2. 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 189027103 636 VTKAYFAKQADEITLQQADVVLVL-QEEDGWLYGERLRDGETGWFPESF 683
Cdd:cd11784    4 ALHSYSAHRPEELELQKGEGVRVLgKFQEGWLRGLSLVTGRVGIFPSNY 52

First Src Homology 3 domain of FCH and double SH3 domains proteins; This group is composed of FCH and double SH3 domains protein 1 (FCHSD1) and FCHSD2. These proteins have a common domain structure consisting of an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs), two SH3, and C-terminal proline-rich domains. They have only been characterized in silico and their functions remain unknown. This group also includes the insect protein, nervous wreck, which acts as a regulator of synaptic growth signaling. 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 189027103 636 VTKAYFAKQADEITLQQADVVLVLQE--EDGWLYGeRLRDGETGWFPESF 683
Cdd:cd11761    6 VLYSYEAQRPDELTITEGEELEVIEDgdGDGWVKA-RNKSGEVGYVPENY 54

Src Homology 3 domain of Brain-specific Angiogenesis Inhibitor 1-Associated Protein 2-Like 2; BAIAP2L2 co-localizes with clathrin plaques but its function has not been determined. It contains an N-terminal IMD or Inverse-Bin/Amphiphysin/Rvs (I-BAR) domain, an SH3 domain, and a WASP homology 2 (WH2) actin-binding motif at the C-terminus. The related proteins, BAIAP2L1 and IRSp53, function as regulators of membrane dynamics and the actin cytoskeleton. 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 189027103 648 ITLQQADV--VLVLQEEDGWLYGERLRDGETGWFPESF 683
Cdd:cd11914   18 LRFNRGDIitVLVPEARNGWLYGKLEGSSRQGWFPEAY 55

Src Homology 3 domain of Sdc25/Cdc25 guanine nucleotide exchange factors; This subfamily is composed of the Saccharomyces cerevisiae guanine nucleotide exchange factors (GEFs) Sdc25 and Cdc25, and similar proteins. These GEFs regulate Ras by stimulating the GDP/GTP exchange on Ras. Cdc25 is involved in the Ras/PKA pathway that plays an important role in the regulation of metabolism, stress responses, and proliferation, depending on available nutrients and conditions. Proteins in this subfamily contain an N-terminal SH3 domain as well as REM (Ras exchanger motif) and RasGEF domains at the C-terminus. 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 189027103 634 VEVTKAYFAKQADEITLQQADVVLVL-QEEDGW---LYGERLRDGETGWFPESF 683
Cdd:cd11883    2 VVALYDFTPKSKNQLSFKAGDIIYVLnKDPSGWwdgVIISSSGKVKRGWFPSNY 55

Src Homology 3 domain of Class A and B Dedicator of Cytokinesis proteins; DOCK proteins are atypical guanine nucleotide exchange factors (GEFs) that lack the conventional Dbl homology (DH) domain. They are divided into four classes (A-D) based on sequence similarity and domain architecture: class A includes Dock1, 2 and 5; class B includes Dock3 and 4; class C includes Dock6, 7, and 8; and class D includes Dock9, 10 and 11. All DOCKs contain two homology domains: the DHR-1 (Dock homology region-1), also called CZH1 (CED-5, Dock180, and MBC-zizimin homology 1), and DHR-2 (also called CZH2 or Docker). The DHR-1 domain binds phosphatidylinositol-3,4,5-triphosphate while DHR-2 contains the catalytic activity for Rac and/or Cdc42. This subfamily includes only Class A and B DOCKs, which also contain an SH3 domain at the N-terminal region and a PxxP motif at the C-terminus. Class A/B DOCKs are mostly specific GEFs for Rac, except Dock4 which activates the Ras family GTPase Rap1, probably indirectly through interaction with Rap regulatory proteins. The SH3 domain of class A/B DOCKs have been shown to bind Elmo, a scaffold protein that promotes GEF activity of DOCKs by releasing DHR-2 autoinhibition by the intramolecular SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 189027103 640 YFAKQADEITLQQADVVLVLQEEDGWLYGERLRD-GETGWFPESFAH 685
Cdd:cd11872    8 FQGDGEHQLSLQVGDTVQILEECEGWYRGFSLRNkSLKGIFPKSYVH 54

Src Homology 3 domain of beta-Pak Interactive eXchange factor; Beta-PIX, also called Rho guanine nucleotide exchange factor 7 (ARHGEF7) or Cool (Cloned out of Library)-1, activates small GTPases by exchanging bound GDP for free GTP. It acts as a GEF for both Cdc42 and Rac 1, and plays important 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.

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gi 189027103 636 VTKAYFAKQA---DEITLQQADVVLVL-QEEDGWLYGERlrDGETGWFPESF 683
Cdd:cd12061    1 VVRAKFNFQQtneDELSFSKGDVIHVTrVEEGGWWEGTH--NGRTGWFPSNY 50