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

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1800082506  16 NQKRSLYVRAMFDYDKSKDSGLPSQGLSFKYGDILHVINASDDEWWQARRVMLEGDSEEMGVIPSKRRVERKER 89
Cdd:cd12032     1 NQKRSLYVRAMFDYEKSKDSGLPSQGLSFRYGDILHVINASDDEWWQARRVTPDGDSEEMGVIPSKRRVERKER 74

Guanylate kinase homologues; Active enzymes catalyze ATP-dependent phosphorylation of GMP to GDP. Structure resembles that of adenylate kinase. So-called membrane-associated guanylate kinase homologues (MAGUKs) do not possess guanylate kinase activities; instead at least some possess protein-binding functions.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506  172 KDRINDDLISEFPDKFGSCVPHTTRPKRDYEVDGRDYHFViSREQMEKDIQEHKFIEAGQYNDNLYGTSVQSVRFVAERG 251
Cdd:smart00072   5 KGTLLAELIQEIPDAFERVVSHTTRPPRPGEVNGVDYHFV-SKEEFEDDIKSGLFLEWGEYEGNYYGTSKETIRQVAEKG 83

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506  252 KHCILDVSGNAIKRLQVAQLYPIAIFIKPRSLEPLMEMNKRLTEEQAKKTYDRAIKLEQEFGEY--FTAIVQGDTLEDIY 329
Cdd:smart00072  84 KHCLLDIDPQGVKQLRKAQLYPIVIFIAPPSSEELERRLRQRGTETSERIQKRLAAAQKEAQEYhlFDYVIVNDDLEDAY 163

                          170
                   ....*....|
gi 1800082506  330 NQCKLVIEEQ 339
Cdd:smart00072 164 EELKEILEAE 173

guanylate kinase

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 160 NYTRPVIILGPM---KDRINDDLISEFPDKFGSCVPHTTRPKRDYEVDGRDYHFViSREQMEKDIQEHKFIEAGQYNDNL 236
Cdd:PLN02772  133 NAEKPIVISGPSgvgKGTLISMLMKEFPSMFGFSVSHTTRAPREMEKDGVHYHFT-ERSVMEKEIKDGKFLEFASVHGNL 211

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 237 YGTSVQSVRFVAERGKHCILDVSGNAIKRLQVAQLYPIAIFIKPRSLEplmEMNKRL------TEEQAKKTYDRAiKLEQ 310
Cdd:PLN02772  212 YGTSIEAVEVVTDSGKRCILDIDVQGARSVRASSLEAIFIFICPPSME---ELEKRLrargteTEEQIQKRLRNA-EAEL 287

                         170       180
                  ....*....|....*....|....*.
gi 1800082506 311 EFGE---YFTAIVQGDTLEDIYNQCK 333
Cdd:PLN02772  288 EQGKssgIFDHILYNDNLEECYKNLK 313

guanylate kinase; Members of this family are the enzyme guanylate kinase, also called GMP kinase. This enzyme transfers a phosphate from ATP to GMP, yielding ADP and GDP. [Purines, pyrimidines, nucleosides, and nucleotides, Nucleotide and nucleoside interconversions]

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 163 RPVIILGPM---KDRINDDLISEFPDKFGScVPHTTRPKRDYEVDGRDYHFViSREQMEKDIQEHKFIEAGQYNDNLYGT 239
Cdd:TIGR03263   1 LLIVISGPSgagKSTLVKALLEEDPNLKFS-ISATTRKPRPGEVDGVDYFFV-SKEEFEEMIKAGEFLEWAEVHGNYYGT 78

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 240 SVQSVRFVAERGKHCIL--DVSGnaikRLQVAQLYP--IAIFIKPRSLEplmEMNKRL------TEEQAKKTYDRAIKlE 309
Cdd:TIGR03263  79 PKSPVEEALAAGKDVLLeiDVQG----ARQVKKKFPdaVSIFILPPSLE---ELERRLrkrgtdSEEVIERRLAKAKK-E 150

                         170       180
                  ....*....|....*....|....*....
gi 1800082506 310 QEFGEYFTAIVQGDTLEDIYNQCKLVIEE 338
Cdd:TIGR03263 151 IAHADEFDYVIVNDDLEKAVEELKSIILA 179

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 1800082506   22 YVRAMFDYDKSKDsglpsQGLSFKYGDILHVINASDDEWWQARRvmlegDSEEMGVIPS 80
Cdd:smart00326   4 QVRALYDYTAQDP-----DELSFKKGDIITVLEKSDDGWWKGRL-----GRGKEGLFPS 52

Guanylate kinase homologues; Active enzymes catalyze ATP-dependent phosphorylation of GMP to GDP. Structure resembles that of adenylate kinase. So-called membrane-associated guanylate kinase homologues (MAGUKs) do not possess guanylate kinase activities; instead at least some possess protein-binding functions.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506  172 KDRINDDLISEFPDKFGSCVPHTTRPKRDYEVDGRDYHFViSREQMEKDIQEHKFIEAGQYNDNLYGTSVQSVRFVAERG 251
Cdd:smart00072   5 KGTLLAELIQEIPDAFERVVSHTTRPPRPGEVNGVDYHFV-SKEEFEDDIKSGLFLEWGEYEGNYYGTSKETIRQVAEKG 83

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506  252 KHCILDVSGNAIKRLQVAQLYPIAIFIKPRSLEPLMEMNKRLTEEQAKKTYDRAIKLEQEFGEY--FTAIVQGDTLEDIY 329
Cdd:smart00072  84 KHCLLDIDPQGVKQLRKAQLYPIVIFIAPPSSEELERRLRQRGTETSERIQKRLAAAQKEAQEYhlFDYVIVNDDLEDAY 163

                          170
                   ....*....|
gi 1800082506  330 NQCKLVIEEQ 339
Cdd:smart00072 164 EELKEILEAE 173

Src Homology 3 domain of Disks large homolog proteins; The DLG-like proteins are scaffolding proteins that cluster at synapses and are also called PSD (postsynaptic density)-95 proteins or SAPs (synapse-associated proteins). They play important roles in synaptic development and plasticity, cell polarity, migration and proliferation. They are members of the MAGUK (membrane-associated guanylate kinase) protein family, which is characterized by the presence of a core of three domains: PDZ, SH3, and guanylate kinase (GuK). The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. DLG-like proteins contain three PDZ domains and varying N-terminal regions. All DLG proteins exist as alternatively-spliced isoforms. Vertebrates contain four DLG proteins from different genes, called DLG1-4. DLG4 and DLG2 are found predominantly at postsynaptic sites and they mediate surface ion channel and receptor clustering. DLG3 is found axons and some presynaptic terminals. DLG1 interacts with AMPA-type glutamate receptors and is critical in their maturation and delivery to synapses. The SH3 domain of DLG4 binds and clusters the kainate subgroup of glutamate receptors via two proline-rich sequences in their C-terminal tail. It also binds AKAP79/150 (A-kinase anchoring protein). SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1800082506  22 YVRAMFDYDKSKDSGLPSQGLSFKYGDILHVINASDDEWWQARRVMLEGDSEEMGVIPSKR 82
Cdd:cd11861     1 YVRALFDYDPSRDSGLPSQGLSFKFGDILHVTNASDDEWWQARRVTPNGEEEEVGVIPSKR 61

guanylate kinase

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 160 NYTRPVIILGPM---KDRINDDLISEFPDKFGSCVPHTTRPKRDYEVDGRDYHFViSREQMEKDIQEHKFIEAGQYNDNL 236
Cdd:PLN02772  133 NAEKPIVISGPSgvgKGTLISMLMKEFPSMFGFSVSHTTRAPREMEKDGVHYHFT-ERSVMEKEIKDGKFLEFASVHGNL 211

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 237 YGTSVQSVRFVAERGKHCILDVSGNAIKRLQVAQLYPIAIFIKPRSLEplmEMNKRL------TEEQAKKTYDRAiKLEQ 310
Cdd:PLN02772  212 YGTSIEAVEVVTDSGKRCILDIDVQGARSVRASSLEAIFIFICPPSME---ELEKRLrargteTEEQIQKRLRNA-EAEL 287

                         170       180
                  ....*....|....*....|....*.
gi 1800082506 311 EFGE---YFTAIVQGDTLEDIYNQCK 333
Cdd:PLN02772  288 EQGKssgIFDHILYNDNLEECYKNLK 313

Src Homology 3 domain of Disks Large homolog 4; DLG4, also called postsynaptic density-95 (PSD95) or synapse-associated protein 90 (SAP90), is a scaffolding protein that clusters at synapses and plays an important role in synaptic development and plasticity. It is responsible for the membrane clustering and retention of many transporters and receptors such as potassium channels and PMCA4b, a P-type ion transport ATPase, among others. DLG4 is a member of the MAGUK (membrane-associated guanylate kinase) protein family, which is characterized by the presence of a core of three domains: PDZ, SH3, and guanylate kinase (GuK). The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. DLG4 contains three PDZ domains. The SH3 domain of DLG4 binds and clusters the kainate subgroup of glutamate receptors via two proline-rich sequences in their C-terminal tail. It also binds AKAP79/150 (A-kinase anchoring protein). SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 1800082506  22 YVRAMFDYDKSKDSGLPSQGLSFKYGDILHVINASDDEWWQARRVMLEGDSEEMGVIPSKRRVE 85
Cdd:cd12030     3 YIRALFDYDKTKDCGFLSQALSFRFGDVLHVIDAGDEEWWQARRVHSDSETEEIGFIPSKRRVE 66

guanylate kinase; Members of this family are the enzyme guanylate kinase, also called GMP kinase. This enzyme transfers a phosphate from ATP to GMP, yielding ADP and GDP. [Purines, pyrimidines, nucleosides, and nucleotides, Nucleotide and nucleoside interconversions]

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 163 RPVIILGPM---KDRINDDLISEFPDKFGScVPHTTRPKRDYEVDGRDYHFViSREQMEKDIQEHKFIEAGQYNDNLYGT 239
Cdd:TIGR03263   1 LLIVISGPSgagKSTLVKALLEEDPNLKFS-ISATTRKPRPGEVDGVDYFFV-SKEEFEEMIKAGEFLEWAEVHGNYYGT 78

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 240 SVQSVRFVAERGKHCIL--DVSGnaikRLQVAQLYP--IAIFIKPRSLEplmEMNKRL------TEEQAKKTYDRAIKlE 309
Cdd:TIGR03263  79 PKSPVEEALAAGKDVLLeiDVQG----ARQVKKKFPdaVSIFILPPSLE---ELERRLrkrgtdSEEVIERRLAKAKK-E 150

                         170       180
                  ....*....|....*....|....*....
gi 1800082506 310 QEFGEYFTAIVQGDTLEDIYNQCKLVIEE 338
Cdd:TIGR03263 151 IAHADEFDYVIVNDDLEKAVEELKSIILA 179

guanylate kinase; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 191 VPHTTRPKRDYEVDGRDYHFViSREQMEKDIQEHKFIEAGQYNDNLYGTSVQSVRFVAERGKHCIL--DVSGnAikrLQV 268
Cdd:PRK00300   36 VSATTRAPRPGEVDGVDYFFV-SKEEFEEMIENGEFLEWAEVFGNYYGTPRSPVEEALAAGKDVLLeiDWQG-A---RQV 110

                          90       100
                  ....*....|....*....|....*...
gi 1800082506 269 AQLYP--IAIFIKPRSLEplmEMNKRLT 294
Cdd:PRK00300  111 KKKMPdaVSIFILPPSLE---ELERRLR 135

Src Homology 3 domain of Membrane Protein, Palmitoylated 1 (or MAGUK p55 subfamily member 1)-like proteins; This subfamily includes MPP1, CASK (Calcium/calmodulin-dependent Serine protein Kinase), Caenorhabditis elegans lin-2, and similar proteins. MPP1 and CASK are scaffolding proteins from the MAGUK (membrane-associated guanylate kinase) protein family, which is characterized by the presence of a core of three domains: PDZ, SH3, and guanylate kinase (GuK). In addition, they also have the Hook (Protein 4.1 Binding) motif in between the SH3 and GuK domains. The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. CASK and lin-2 also contain an N-terminal calmodulin-dependent kinase (CaMK)-like domain and two L27 domains. MPP1 is ubiquitously-expressed and plays roles in regulating neutrophil polarity, cell shape, hair cell development, and neural development and patterning of the retina. CASK is highly expressed in the mammalian nervous system and plays roles in synaptic protein targeting, neural development, and gene expression regulation. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1800082506  22 YVRAMFDYDKSKDSGLPSQ--GLSFKYGDILHVINASDDEWWQARrvmLEGDSEEM-GVIPS 80
Cdd:cd12035     1 YVRAQFDYDPSKDDLIPCQqaGIAFKTGDILQIISKDDHNWWQAR---KPGASKEPaGLIPS 59

Src Homology 3 domain of Membrane Protein, Palmitoylated 7 (or MAGUK p55 subfamily member 7); MPP7 is a scaffolding protein that binds to DLG1 and promotes tight junction formation and epithelial cell polarity. Mutations in the MPP7 gene may be associated with the pathogenesis of diabetes and extreme bone mineral density. It is one of seven vertebrate homologs of the Drosophila Stardust protein, which is required in establishing cell polarity, and it contains two L27 domains followed by the core of three domains characteristic of MAGUK (membrane-associated guanylate kinase) proteins: PDZ, SH3, and guanylate kinase (GuK). The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1800082506  22 YVRAMFDYDKSKDSGLPSQ--GLSFKYGDILHVINASDDEWWQARrvmLEGDSE-EMGVIPSK 81
Cdd:cd12033     1 FIKALFDYNPNEDKAIPCKeaGLSFKKGDILQIMSQDDATWWQAK---HEGDANpRAGLIPSK 60

guanylate kinase; Provisional

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 153 PVTRQEINYTRPVIILGPM---KDRINDDLiSEFPDKFGSCVPHTTRPKRDYEVDGRDYHFViSREQMEKDIQEHKFIEA 229
Cdd:PRK14738    4 PWLFNKPAKPLLVVISGPSgvgKDAVLARM-RERKLPFHFVVTATTRPKRPGEIDGVDYHFV-TPEEFREMISQNELLEW 81

                          90       100       110       120       130       140       150
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1800082506 230 GQYNDNLYGTSVQSVRFVAERGKHCIL--DVSGNA-IKRLqVAQlyPIAIFIKPRSLEPLM-EMNKRLTE 295
Cdd:PRK14738   82 AEVYGNYYGVPKAPVRQALASGRDVIVkvDVQGAAsIKRL-VPE--AVFIFLAPPSMDELTrRLELRRTE 148

Src Homology 3 domain of Calcium/calmodulin-dependent Serine protein Kinase; CASK is a scaffolding protein that is highly expressed in the mammalian nervous system and plays roles in synaptic protein targeting, neural development, and gene expression regulation. CASK interacts with many different binding partners including parkin, neurexin, syndecans, calcium channel proteins, caskin, among others, to perform specific functions in different subcellular locations. Disruption of the CASK gene in mice results in neonatal lethality while mutations in the human gene have been associated with X-linked mental retardation. Drosophila CASK is associated with both pre- and postsynaptic membranes and is crucial in synaptic transmission and vesicle cycling. CASK contains an N-terminal calmodulin-dependent kinase (CaMK)-like domain, two L27 domains, followed by the core of three domains characteristic of MAGUK (membrane-associated guanylate kinase) proteins: PDZ, SH3, and guanylate kinase (GuK). In addition, it also contains the Hook (Protein 4.1 Binding) motif in between the SH3 and GuK domains. The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1800082506  22 YVRAMFDYDKSKDSGLPSQ--GLSFKYGDILHVINASDDEWWQARRVMLEGDseEMGVIPS 80
Cdd:cd12081     1 YVRAQFEYDPLKDDLIPCKqaGIRFRVGDILQIISKDDHNWWQAKLENSKNG--TAGLIPS 59

Src Homology 3 domain of Membrane Protein, Palmitoylated 4 (or MAGUK p55 subfamily member 4); MPP4, also called Disks Large homolog 6 (DLG6) or Amyotrophic lateral sclerosis 2 chromosomal region candidate gene 5 protein (ALS2CR5), is a retina-specific scaffolding protein that plays a role in organizing presynaptic protein complexes in the photoreceptor synapse, where it localizes to the plasma membrane. It is required in the proper localization of calcium ATPases and for maintenance of calcium homeostasis. MPP4 is one of seven vertebrate homologs of the Drosophila Stardust protein, which is required in establishing cell polarity, and it contains two L27 domains followed by the core of three domains characteristic of MAGUK (membrane-associated guanylate kinase) proteins: PDZ, SH3, and guanylate kinase (GuK). The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1800082506  22 YVRAMFDYDKSKDSGLP--SQGLSFKYGDILHVINASDDEWWQARRvmLEGDSEEMGVIPS 80
Cdd:cd12034     1 YVRAMVDYWPQQDPSIPcaDAGLPFRKGDILQIVDQNDSLWWQARK--LSDLAACAGLIPS 59

Src Homology 3 domain of Membrane Protein, Palmitoylated 6 (or MAGUK p55 subfamily member 6); MPP6, also called Veli-associated MAGUK 1 (VAM-1) or PALS2, is a scaffolding protein that binds to Veli-1, a homolog of Caenorhabditis Lin-7. It is one of seven vertebrate homologs of the Drosophila Stardust protein, which is required in establishing cell polarity, and it contains two L27 domains followed by the core of three domains characteristic of MAGUK (membrane-associated guanylate kinase) proteins: PDZ, SH3, and guanylate kinase (GuK). In addition, it also contains the Hook (Protein 4.1 Binding) motif in between the SH3 and GuK domains. The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1800082506  22 YVRAMFDYDKSKDSGLPSQ--GLSFKYGDILHVINASDDEWWQARRVMlEGDSEemGVIPSK 81
Cdd:cd12038     1 FVKCHFDYNPYNDNLIPCKeaGLKFSKGEILQIVNREDPNWWQASHVK-EGGSA--GLIPSQ 59

SH3 domain; SH3 (Src homology 3) domains are often indicative of a protein involved in signal transduction related to cytoskeletal organization. First described in the Src cytoplasmic tyrosine kinase. The structure is a partly opened beta barrel.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 1800082506  24 RAMFDYDKSKDSGLpsqglSFKYGDILHVINASDDEWWQARRvmlegDSEEMGVIPS 80
Cdd:pfam00018   1 VALYDYTAQEPDEL-----SFKKGDIIIVLEKSEDGWWKGRN-----KGGKEGLIPS 47

Src homology 3 domain of the Tight junction proteins, Zonula occludens (ZO) proteins; ZO proteins are scaffolding proteins that associate with each other and with other proteins of the tight junction, zonula adherens, and gap junctions. They play roles in regulating cytoskeletal dynamics at these cell junctions. They are considered members of the MAGUK (membrane-associated guanylate kinase) protein family, which is characterized by the presence of a core of three domains: PDZ, SH3, and guanylate kinase (GuK). The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. Vertebrates contain three ZO proteins (ZO-1, ZO-2, and ZO-3) with redundant and non-redundant roles. They contain three PDZ domains, followed by SH3 and GuK domains; in addition, ZO-1 and ZO-2 contains a proline-rich (PR) actin binding domain at the C-terminus while ZO-3 contains this PR domain between the second and third PDZ domains. The C-terminal regions of the three ZO proteins are unique. The SH3 domain of ZO-1 has been shown to bind ZONAB, ZAK, afadin, and Galpha12. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1800082506  22 YVRAMFDYDKSkdsglPSQGLSFKYGDILHVINASDDE---WWQARRVMLEGDSEEMGVIPSKRRVE 85
Cdd:cd11859     1 YIRTHFDYEKP-----AKGELSFKKGEVFHVVDTLYQGtvgSWQAVRVGRNHQELERGVIPNKSRAE 62

Src homology 3 domain of High osmolarity signaling protein Sho1p; Sho1p (or Sho1), also called SSU81 (Suppressor of SUA8-1 mutation), is a yeast membrane protein that regulates adaptation to high salt conditions by activating the HOG (high-osmolarity glycerol) pathway. High salt concentrations lead to the localization to the membrane of the MAPKK Pbs2, which is then activated by the MAPKK Ste11 and in turn, activates the MAPK Hog1. Pbs2 is localized to the membrane though the interaction of its PxxP motif with the SH3 domain of Sho1p. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity. 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 1800082506  23 VRAMFDYDKSKDSglPSQgLSFKYGDILHVINASdDEWWQARRvmlegDSEEMGVIPS 80
Cdd:cd11855     2 ARALYPYDASPDD--PNE-LSFEKGEILEVSDTS-GKWWQARK-----SNGETGICPS 50

N-terminal Src Homology 3 domain of Ct10 Regulator of Kinase adaptor proteins; CRK adaptor proteins consists of SH2 and SH3 domains, which bind tyrosine-phosphorylated peptides and proline-rich motifs, respectively. They function downstream of protein tyrosine kinases in many signaling pathways started by various extracellular signals, including growth and differentiation factors. Cellular CRK (c-CRK) contains a single SH2 domain, followed by N-terminal and C-terminal SH3 domains. It is involved in the regulation of many cellular processes including cell growth, motility, adhesion, and apoptosis. CRK has been implicated in the malignancy of various human cancers. The N-terminal SH3 domain of CRK binds a number of target proteins including DOCK180, C3G, SOS, and cABL. The CRK family includes two alternatively spliced protein forms, CRKI and CRKII, that are expressed by the CRK gene, and the CRK-like (CRKL) protein, which is expressed by a distinct gene (CRKL). 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 1800082506  22 YVRAMFDYDKSKDSGLPsqglsFKYGDILHVINASDDEWWQARrvmlegDSE-EMGVIP 79
Cdd:cd11758     2 YVRALFDFPGNDDEDLP-----FKKGEILTVIRKPEEQWWNAR------NSEgKTGMIP 49

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.

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gi 1800082506  22 YVRAMFDYDKSKDSGLpsqglSFKYGDILHVINASDDEWWQ 62
Cdd:cd11949     1 YVQALFDFDPQEDGEL-----GFRRGDFIEVMDNSDPNWWK 36

Src homology 3 domain of Abl Interactor proteins; Abl interactor (Abi) proteins are adaptor proteins serving as binding partners and substrates of Abl tyrosine kinases. They are involved in regulating actin cytoskeletal reorganization and play important roles in membrane-ruffling, endocytosis, cell motility, and cell migration. They localize to sites of actin polymerization in epithelial adherens junction and immune synapses, as well as to the leading edge of lamellipodia. Vertebrates contain two Abi proteins, Abi1 and Abi2. Abi1 displays a wide expression pattern while Abi2 is highly expressed in the eye and brain. Abi proteins contain a homeobox homology domain, a proline-rich region, and a SH3 domain. The SH3 domain of Abi binds to a PxxP motif in Abl. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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gi 1800082506  22 YVRAMFDYDKSKDSGLpsqglSFKYGDILHVINASDDEWWQ 62
Cdd:cd11826     1 KVVALYDYTADKDDEL-----SFQEGDIIYVTKKNDDGWYE 36

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.

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gi 1800082506  22 YVRAMFDYDKSKDSGLPsqglsFKYGDILHVINASDDEWWQAR 64
Cdd:cd11951     1 FVQAQYDFSAEDPSQLS-----FRRGDIIEVLDCPDPNWWRGR 38

Src homology 3 domain of Signal Transducing Adaptor Molecule 1; STAM1 is part of the endosomal sorting complex required for transport (ESCRT-0) and is involved in sorting ubiquitinated cargo proteins from the endosome. It may also be involved in the regulation of IL2 and GM-CSF mediated signaling, and has been implicated in neural cell survival. 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. 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 1800082506  23 VRAMFDYDKSKDSGLpsqglSFKYGDILHVINASDDEWWQarrvmleGDSEE-MGVIPS 80
Cdd:cd11964     3 VRAIYDFEAAEDNEL-----TFKAGDIITILDDSDPNWWK-------GETPQgTGLFPS 49

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.

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gi 1800082506  22 YVRAMFDYDKSKdsglPSQgLSFKYGDILHVINASDDEWWQAR 64
Cdd:cd11805     1 RVQALYDFNPQE----PGE-LEFRRGDIITVLDSSDPDWWKGE 38

Src homology 3 domain of Signal Transducing Adaptor Molecule 2; STAM2, also called EAST (Epidermal growth factor receptor-associated protein with SH3 and TAM domain) or Hbp (Hrs binding protein), is part of the endosomal sorting complex required for transport (ESCRT-0). It plays a role in sorting mono-ubiquinated endosomal cargo for trafficking to the lysosome for degradation. It is also involved in the regulation of exocytosis. 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. 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 1800082506  23 VRAMFDYDKSKDSGLpsqglSFKYGDILHVINASDDEWWQARrvmlegDSEEMGVIPS 80
Cdd:cd11963     4 VRALYDFEAVEDNEL-----TFKHGEIIIVLDDSDANWWKGE------NHRGVGLFPS 50

Src homology 3 domain of ArfGAP with SH3 domain, ankyrin repeat and PH domain containing proteins; ASAPs are Arf GTPase activating proteins (GAPs) and they function in regulating cell growth, migration, and invasion. They contain an N-terminal BAR domain, followed by a Pleckstrin homology (PH) domain, an Arf GAP domain, ankyrin (ANK) repeats, and a C-terminal SH3 domain. Vertebrates contain at least three members, ASAP1, ASAP2, and ASAP3, but some ASAP3 proteins do not seem to harbor a C-terminal SH3 domain. ASAP1 and ASAP2 show GTPase activating protein (GAP) activity towards Arf1 and Arf5. They do not show GAP activity towards Arf6, but are able to mediate Arf6 signaling by binding stably to GTP-Arf6. ASAP3 is an Arf6-specific GAP. 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 1800082506  23 VRAMfdYDKSKDSglpSQGLSFKYGDILHVINASDDEWWQArrvMLEGDSEEMGVIPS 80
Cdd:cd11821     2 VRAL--YDCQADN---DDELTFSEGEIIVVTGEEDDEWWEG---HIEGDPSRRGVFPV 51

Src homology 3 domain of Slit-Robo GTPase Activating Protein 4; srGAP4, also called ARHGAP4, is highly expressed in hematopoietic cells and may play a role in lymphocyte differentiation. It is able to stimulate the GTPase activity of Rac1, Cdc42, and RhoA. In the nervous system, srGAP4 has been detected in differentiating neurites and may be involved in axon and dendritic growth. srGAPs are Rho GAPs that interact with Robo1, the transmembrane receptor of Slit proteins. Slit proteins are secreted proteins that control axon guidance and the migration of neurons and leukocytes. srGAPs contain an N-terminal F-BAR domain, a Rho GAP 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.

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gi 1800082506  25 AMFDYdkskdSGLPSQGLSFKYGDILHVINASDDEWWQarrvmleGDSEEM-GVIPSK 81
Cdd:cd11956     6 ACFDY-----TGRTAQELSFKRGDVLLLHSKASSDWWR-------GEHNGMrGLIPHK 51

Src homology 3 domain of Fyn and Yrk Protein Tyrosine Kinases; Fyn and Yrk (Yes-related kinase) are members of the Src subfamily of proteins, which are cytoplasmic (or non-receptor) PTKs. Fyn, together with Lck, plays a critical role in T-cell signal transduction by phosphorylating ITAM (immunoreceptor tyr activation motif) sequences on T-cell receptors, ultimately leading to the proliferation and differentiation of T-cells. In addition, Fyn is involved in the myelination of neurons, and is implicated in Alzheimer's and Parkinson's diseases. Yrk has been detected only in chickens. It is primarily found in neuronal and epithelial cells and in macrophages. It may play a role in inflammation and in response to injury. Src kinases contain an N-terminal SH4 domain with a myristoylation site, followed by SH3 and SH2 domains, a tyr kinase domain, and a regulatory C-terminal region containing a conserved tyr. They are activated by autophosphorylation at the tyr kinase domain, but are negatively regulated by phosphorylation at the C-terminal tyr by Csk (C-terminal Src Kinase). The SH3 domain of Src kinases contributes to substrate recruitment by binding adaptor proteins/substrates, and regulation of kinase activity through an intramolecular interaction. 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 1800082506  20 SLYVrAMFDYD-KSKDSglpsqgLSFKYGDILHVINASDDEWWQARRVMlegdSEEMGVIPS 80
Cdd:cd12006     1 TLFV-ALYDYEaRTEDD------LSFHKGEKFQILNSSEGDWWEARSLT----TGETGYIPS 51

Src Homology 3 domain of Voltage-dependent L-type calcium channel subunit beta-1; The beta1 subunit of voltage-dependent calcium channels (Ca(V)s) is one of four beta subunits present in vertebrates. It is the only beta subunit, as the beta1a variant, expressed in skeletal muscle; the beta1b variant is also widely expressed in other tissues including the heart and brain. Knockout of the beta1 gene in mice results in embryonic lethality, demonstrating its importance in development. Ca(V)s are multi-protein complexes that regulate the entry of calcium into cells. They impact muscle contraction, neuronal migration, hormone and neurotransmitter release, and the activation of calcium-dependent signaling pathways. They are composed of four subunits: alpha1, alpha2delta, beta, and gamma. The beta subunit is a soluble and intracellular protein that interacts with the transmembrane alpha1 subunit. It facilitates the trafficking and proper localization of the alpha1 subunit to the cellular plasma membrane. Vertebrates contain four different beta subunits from distinct genes (beta1-4); each exists as multiple splice variants. All are expressed in the brain while other tissues show more specific expression patterns. The beta subunits show similarity to MAGUK (membrane-associated guanylate kinase) proteins in that they contain SH3 and inactive guanylate kinase (GuK) domains; however, they do not appear to contain a PDZ 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 1800082506  23 VRAMFDYDKSKDSGLPSQGL--SFKYGDILHVINASDDEWWQARRVMlEGDseEMGVIPSKRRVE 85
Cdd:cd12041     7 VRTNVGYNPSPGDDVPVQGMaiSFEPKDFLHIKEKYNNDWWIGRLVK-EGC--EVGFIPSPVKLE 68

Src Homology 3 domain of Rho GTPase-activating protein 9 and similar proteins; This subfamily is composed of Rho GTPase-activating proteins including mammalian ARHGAP9, and vertebrate ARHGAPs 12 and 27. RhoGAPs (or ARHGAPs) bind to Rho proteins and enhance the hydrolysis rates of bound GTP. ARHGAP9 functions as a GAP for Rac and Cdc42, but not for RhoA. It negatively regulates cell migration and adhesion. It also acts as a docking protein for the MAP kinases Erk2 and p38alpha, and may facilitate cross-talk between the Rho GTPase and MAPK pathways to control actin remodeling. ARHGAP27, also called CAMGAP1, shows GAP activity towards Rac1 and Cdc42. It binds the adaptor protein CIN85 and may play a role in clathrin-mediated endocytosis. ARHGAP12 has been shown to display GAP activity towards Rac1. It plays a role in regulating HFG-driven cell growth and invasiveness. ARHGAPs in this subfamily contain SH3, WW, Pleckstin homology (PH), and RhoGAP domains. 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 1800082506  22 YVRAMFDYD-KSKDSglpsQGLSFKYGDILHVINASDDEWWQARRvmlEGDSEEMGV 77
Cdd:cd11888     1 YVVVLYPFEyTGKDG----RKVSIKEGERFLLLKKSNDDWWQVRR---PGDSKPFYV 50

Src homology 3 domain of RUN and SH3 domain-containing protein 1; RUSC1, also called NESCA (New molecule containing SH3 at the carboxy-terminus), is highly expressed in the brain and is translocated to the nuclear membrane from the cytoplasm upon stimulation with neurotrophin. It plays a role in facilitating neurotrophin-dependent neurite outgrowth. It also interacts with NEMO (or IKKgamma) and may function in NEMO-mediated activation of NF-kB. RUSC proteins are adaptor proteins consisting of RUN, leucine zipper, and SH3 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 1800082506  23 VRAMFDYDKSKDsglpsqGLSFKYGDILHVINASDDEWWQARRvmleGDSEemGVIP 79
Cdd:cd11958     2 VRALCDHAGSES------QLSFRKGEELQVLGTVDEDWIRCRR----GDRE--GLVP 46

Src Homology 3 domain of C-terminal Src kinase; CSK is a cytoplasmic (or nonreceptor) tyr kinase containing the Src homology domains, SH3 and SH2, N-terminal to the catalytic tyr kinase domain. They negatively regulate the activity of Src kinases that are anchored to the plasma membrane. To inhibit Src kinases, CSK is translocated to the membrane via binding to specific transmembrane proteins, G-proteins, or adaptor proteins near the membrane. CSK catalyzes the tyr phosphorylation of the regulatory C-terminal tail of Src kinases, resulting in their inactivation. It is expressed in a wide variety of tissues and plays a role, as a regulator of Src, in cell proliferation, survival, and differentiation, and consequently, in cancer development and progression. In addition, CSK also shows Src-independent functions. It is a critical component in G-protein signaling, and plays a role in cytoskeletal reorganization and cell migration. 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 1800082506  36 GLPSQGLSFKYGDILHVINASDD-EWWQARRVmlegDSEEmGVIP 79
Cdd:cd11769    12 GASEEDLPFKKGDILTIVAVTKDpNWYKAKNK----DGRE-GMIP 51