Second C-terminal Src homology 3 domain of Rho guanine nucleotide exchange factor 37; ARHGEF37 contains a RhoGEF [or Dbl homology (DH)] domain followed by a Bin/Amphiphysin/Rvs (BAR) domain, and two C-terminal SH3 domains. Its specific function is unknown. Its domain architecture is similar to the C-terminal half of DNMBP or Tuba, a cdc42-specific GEF that provides a functional link between dynamin, Rho GTPase signaling, and actin dynamics, and plays an important role in regulating cell junction configuration. GEFs activate small GTPases by exchanging bound GDP for free GTP. 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 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILEAQDKKGNPEWSLVEANGQRGYVPSNFLAR 449
Cdd:cd11941     1 QVVAAYPFTARSKHEVSLQAGQPVTVLEPHDKKGSPEWSLVEVNGQRGYVPSSYLAR 57

Second C-terminal Src homology 3 domain of Rho guanine nucleotide exchange factor 37; ARHGEF37 contains a RhoGEF [or Dbl homology (DH)] domain followed by a Bin/Amphiphysin/Rvs (BAR) domain, and two C-terminal SH3 domains. Its specific function is unknown. Its domain architecture is similar to the C-terminal half of DNMBP or Tuba, a cdc42-specific GEF that provides a functional link between dynamin, Rho GTPase signaling, and actin dynamics, and plays an important role in regulating cell junction configuration. GEFs activate small GTPases by exchanging bound GDP for free GTP. 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 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILEAQDKKGNPEWSLVEANGQRGYVPSNFLAR 449
Cdd:cd11941     1 QVVAAYPFTARSKHEVSLQAGQPVTVLEPHDKKGSPEWSLVEVNGQRGYVPSSYLAR 57

BAR domain;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1907130254   29 LSKKTTRLSQMLKQEAGLVSRTE-DKEFDDLEERFQ----WVSLCVKELRN-------------NVVDFMGNLEVFLSFR 90
Cdd:smart00721   2 FKKQFNRAKQKVGEKVGKAEKTKlDEDFEELERRFDtteaEIEKLQKDTKLylqpnpavraklaSQKKLSKSLGEVYEGG 81

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1907130254   91 PH--ERSLDIPGGPAEQYCSLARDLQLHAFLQFKQRLRSLVWQPLCSLARALAGPQNLIKKRLDKLLDFD---------- 158
Cdd:smart00721  82 DDgeGLGADSSYGKALDKLGEALKKLLQVEESLSQVKRTFILPLLNFLLGEFKEIKKARKKLERKLLDYDsarhklkkak 161

                          170       180       190       200       210       220       230
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1907130254  159 RVEEKLLDVGSVTWEEE--AARHEYQALNSLLVAELPQFNQLVMQWLGQILCTFVVLQ----RDLADqVLRRAESTM 229
Cdd:smart00721 162 KSKEKKKDEKLAKAEEElrKAKQEFEESNAQLVEELPQLVASRVDFFVNCLQALIEAQlnfhRESYK-LLQQLQQQL 237

Variant SH3 domain;

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1907130254 396 AVYPFVARSTHELSLQAGQPVTILEaqdkKGNPEWSLVEANGQRGYVPSNFLA 448
Cdd:pfam14604   1 ALYPYEPKDDDELSLQRGDVITVIE----ESEDGWWEGINTGRTGLVPANYVE 49

Variant 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 1907130254 297 YQVSSNINGTGTLDLTLLRGQIVALLqnkDTKGNNSrWLVDTGGHRGYVPAGKLQLY 353
Cdd:pfam07653   2 GRVIFDYVGTDKNGLTLKKGDVVKVL---GKDNDGW-WEGETGGRVGLVPSTAVEEI 54

Second C-terminal Src homology 3 domain of Rho guanine nucleotide exchange factor 37; ARHGEF37 contains a RhoGEF [or Dbl homology (DH)] domain followed by a Bin/Amphiphysin/Rvs (BAR) domain, and two C-terminal SH3 domains. Its specific function is unknown. Its domain architecture is similar to the C-terminal half of DNMBP or Tuba, a cdc42-specific GEF that provides a functional link between dynamin, Rho GTPase signaling, and actin dynamics, and plays an important role in regulating cell junction configuration. GEFs activate small GTPases by exchanging bound GDP for free GTP. 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 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILEAQDKKGNPEWSLVEANGQRGYVPSNFLAR 449
Cdd:cd11941     1 QVVAAYPFTARSKHEVSLQAGQPVTVLEPHDKKGSPEWSLVEVNGQRGYVPSSYLAR 57

First C-terminal Src homology 3 domain of Rho guanine nucleotide exchange factor 37; ARHGEF37 contains a RhoGEF [or Dbl homology (DH)] domain followed by a Bin/Amphiphysin/Rvs (BAR) domain, and two C-terminal SH3 domains. Its specific function is unknown. Its domain architecture is similar to the C-terminal half of DNMBP or Tuba, a cdc42-specific GEF that provides a functional link between dynamin, Rho GTPase signaling, and actin dynamics, and plays an important role in regulating cell junction configuration. GEFs activate small GTPases by exchanging bound GDP for free GTP. 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 1907130254 296 LYQVSSNINGTGTLDLTLLRGQIVALLQNKDTKGNNSRWLVDTGGHRGYVPAGK 349
Cdd:cd11799     1 IYQVMSNVSGTRDLDLTLTRGEIVAVLQEADTKGNTGRWLVDAGGKRGYVPASK 54

BAR domain;

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1907130254   29 LSKKTTRLSQMLKQEAGLVSRTE-DKEFDDLEERFQ----WVSLCVKELRN-------------NVVDFMGNLEVFLSFR 90
Cdd:smart00721   2 FKKQFNRAKQKVGEKVGKAEKTKlDEDFEELERRFDtteaEIEKLQKDTKLylqpnpavraklaSQKKLSKSLGEVYEGG 81

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1907130254   91 PH--ERSLDIPGGPAEQYCSLARDLQLHAFLQFKQRLRSLVWQPLCSLARALAGPQNLIKKRLDKLLDFD---------- 158
Cdd:smart00721  82 DDgeGLGADSSYGKALDKLGEALKKLLQVEESLSQVKRTFILPLLNFLLGEFKEIKKARKKLERKLLDYDsarhklkkak 161

                          170       180       190       200       210       220       230
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1907130254  159 RVEEKLLDVGSVTWEEE--AARHEYQALNSLLVAELPQFNQLVMQWLGQILCTFVVLQ----RDLADqVLRRAESTM 229
Cdd:smart00721 162 KSKEKKKDEKLAKAEEElrKAKQEFEESNAQLVEELPQLVASRVDFFVNCLQALIEAQlnfhRESYK-LLQQLQQQL 237

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

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILEaqdkKGNPEWSLVEANGQRGYVPSNFL 447
Cdd:cd11856     1 SYVAIADYEAQGDDEISLQEGEVVEVLE----KNDSGWWYVRKGDKEGWVPASYL 51

BAR domain; BAR domains are dimerization, lipid binding and curvature sensing modules found in many different protein families. A BAR domain with an additional N-terminal amphipathic helix (an N-BAR) can drive membrane curvature. These N-BAR domains are found in amphiphysin, endophilin, BRAP and Nadrin. BAR domains are also frequently found alongside domains that determine lipid specificity, like pfam00169 and pfam00787 domains in beta centaurins and sorting nexins respectively.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1907130254  29 LSKKTTRLSQMLKQEAGLVSRTE-DKEFDDLEERFqwvslcvKELRNNVVDFMGNLEVFLS----FRPHERSLDIPG--- 100
Cdd:pfam03114   1 LKKQFNRASQLLGEKVGGAEKTKlDEDFEELERRF-------DTTEKEIKKLQKDTKGYLQpnpgARAKQTVLEQPEell 73

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1907130254 101 -----------------GPAEQYCSLARDLQLHAFLQFKQRLRSLVWQPLCSLARALAGPQNLIKKRLDKLLDFDRVE-- 161
Cdd:pfam03114  74 aesmieagkdlgedssfGKALEDYGEALKRLAQLLEQLDDRVETNFLDPLRNLLKEFKEIQKHRKKLERKRLDYDAAKtr 153

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1907130254 162 -EKLLDVGSVTW------EEE--AARHEYQALNSLLVAELPQFNQLVMQWLGQILCTFVVLQRDL---ADQVLRRAESTM 229
Cdd:pfam03114 154 vKKAKKKKSSKAkdesqaEEElrKAQAKFEESNEQLKALLPNLLSLEVEFVVNQLVAFVEAQLDFhrqCYQLLEQLQQQL 233

                  ..
gi 1907130254 230 AL 231
Cdd:pfam03114 234 GK 235

Src homology 3 domain of Src kinase-like Protein Tyrosine Kinases; Src subfamily members include Src, Lck, Hck, Blk, Lyn, Fgr, Fyn, Yrk, Yes, and Brk. Src (or c-Src) proteins are cytoplasmic (or non-receptor) PTKs which are anchored to the plasma membrane. They 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). However, Brk lacks the N-terminal myristoylation sites. Src proteins are involved in signaling pathways that regulate cytokine and growth factor responses, cytoskeleton dynamics, cell proliferation, survival, and differentiation. They were identified as the first proto-oncogene products, and they regulate cell adhesion, invasion, and motility in cancer cells, and tumor vasculature, contributing to cancer progression and metastasis. Src kinases are overexpressed in a variety of human cancers, making them attractive targets for therapy. They are also implicated in acute inflammatory responses and osteoclast function. Src, Fyn, Yes, and Yrk are widely expressed, while Blk, Lck, Hck, Fgr, Lyn, and Brk show a limited expression pattern. This subfamily also includes Drosophila Src42A, Src oncogene at 42A (also known as Dsrc41) which accumulates at sites of cell-cell or cell-matrix adhesion, and participates in Drosphila development and wound healing. It has been shown to promote tube elongation in the tracheal system, is essential for proper cell-cell matching during dorsal closure, and regulates cell-cell contacts in developing Drosophila eyes. 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.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*.
gi 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILeaqdKKGNPEWSLVE--ANGQRGYVPSNF 446
Cdd:cd11845     1 IYVALYDYEARTDDDLSFKKGDRLQIL----DDSDGDWWLARhlSTGKEGYIPSNY 52

Src Homology 3 domain of Tec-like Protein Tyrosine Kinases; The Tec (Tyrosine kinase expressed in hepatocellular carcinoma) subfamily is composed of Tec, Btk, Bmx (Etk), Itk (Tsk, Emt), Rlk (Txk), and similar proteins. They are cytoplasmic (or nonreceptor) tyr kinases containing Src homology protein interaction domains (SH3, SH2) N-terminal to the catalytic tyr kinase domain. Most Tec subfamily members (except Rlk) also contain an N-terminal pleckstrin homology (PH) domain, which binds the products of PI3K and allows membrane recruitment and activation. In addition, some members contain the Tec homology (TH) domain, which contains proline-rich and zinc-binding regions. Tec kinases are expressed mainly by haematopoietic cells, although Tec and Bmx are also found in endothelial cells. B-cells express Btk and Tec, while T-cells express Itk, Txk, and Tec. Collectively, Tec kinases are expressed in a variety of myeloid cells such as mast cells, platelets, macrophages, and dendritic cells. Each Tec kinase shows a distinct cell-type pattern of expression. The function of Tec kinases in lymphoid cells have been studied extensively. They play important roles in the development, differentiation, maturation, regulation, survival, and function of B-cells and T-cells. 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 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILeaqDKKGNPEWSLVEANGQRGYVPSNFLA 448
Cdd:cd11768     1 IVVALYDFQPIEPGDLPLEKGEEYVVL---DDSNEHWWRARDKNGNEGYIPSNYVT 53

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 1907130254 395 VAVYPFVARSTHELSLQAGQPVTILEaqdkKGNPEWSLVE-ANGQRGYVPS 444
Cdd:pfam00018   1 VALYDYTAQEPDELSFKKGDIIIVLE----KSEDGWWKGRnKGGKEGLIPS 47

Third Src Homology 3 domain of the fungal endocytic adaptor protein Sla1p; Sla1p facilitates endocytosis by playing a role as an adaptor protein in coupling components of the actin cytoskeleton to the endocytic machinery. It interacts with Abp1p, Las17p and Pan1p, which are activator proteins of actin-related protein 2/3 (Arp2/3). Sla1p contains multiple domains including three SH3 domains, a SAM (sterile alpha motif) domain, and a Sla1 homology domain 1 (SHD1), which binds to the NPFXD motif that is found in many integral membrane proteins such as the Golgi-localized Arf-binding protein Lsb5p and the P4-ATPases, Drs2p and Dnf1p. The third SH3 domain of Sla1p can bind ubiquitin while retaining the ability to bind proline-rich ligands; monoubiquitination of target proteins signals internalization and sorting through the endocytic pathway. 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 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILeaqDKKGNPEWSLVE--ANGQRGYVPSNFL 447
Cdd:cd11775     2 RGKVLYDFDAQSDDELTVKEGDVVYIL---DDKKSKDWWMVEnvSTGKEGVVPASYI 55

Second C-terminal Src homology 3 domain of Dynamin Binding Protein, also called Tuba, and similar domains; DNMBP or Tuba is a cdc42-specific guanine nucleotide exchange factor (GEF) that contains four N-terminal SH3 domains, a central RhoGEF [or Dbl homology (DH)] domain followed by a Bin/Amphiphysin/Rvs (BAR) domain, and two C-terminal SH3 domains. It provides a functional link between dynamin, Rho GTPase signaling, and actin dynamics. It plays an important role in regulating cell junction configuration. The C-terminal SH3 domains of DNMBP bind to N-WASP and Ena/VASP proteins, which are key regulatory proteins of the actin cytoskeleton. Also included in this subfamily is the second C-terminal SH3 domain of Rho guanine nucleotide exchange factor 37 (ARHGEF37), whose function is still unknown. 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 1907130254 304 NGTGTLDLTLLRGQIVALLQNKDTKGNNSRWLVDTGGHRGYVPAGKLQ 351
Cdd:cd11800     9 EARSPGELSVTEGQVVTVLEKHDLKGNPEWWLVEDRGKQGYVPSNYLA 56

Src homology 3 domain of Alpha Spectrin; Spectrin is a major structural component of the red blood cell membrane skeleton and is important in erythropoiesis and membrane biogenesis. It is a flexible, rope-like molecule composed of two subunits, alpha and beta, which consist of many spectrin-type repeats. Alpha and beta spectrin associate to form heterodimers and tetramers; spectrin tetramer formation is critical for red cell shape and deformability. Defects in alpha spectrin have been associated with inherited hemolytic anemias including hereditary spherocytosis (HSp), hereditary elliptocytosis (HE), and hereditary pyropoikilocytosis (HPP). Alpha spectrin contains a middle SH3 domain and a C-terminal EF-hand binding motif in addition to multiple spectrin repeats. 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 1907130254 394 VVAVYPFVARSTHELSLQAGQPVTILEAQDKkgnpEWSLVEANGQRGYVPSNFLAR 449
Cdd:cd11808     2 VVALYDYQEKSPREVSMKKGDILTLLNSSNK----DWWKVEVNDRQGFVPAAYVKK 53

Src Homology 3 domain of Bruton's tyrosine kinase; BTK is a cytoplasmic (or nonreceptor) tyr kinase containing Src homology protein interaction domains (SH3, SH2) N-terminal to the catalytic tyr kinase domain. It also contains an N-terminal pleckstrin homology (PH) domain, which binds the products of PI3K and allows membrane recruitment and activation, and the Tec homology (TH) domain with proline-rich and zinc-binding regions. Btk is expressed in B-cells, and a variety of myeloid cells including mast cells, platelets, neutrophils, and dendrictic cells. It interacts with a variety of partners, from cytosolic proteins to nuclear transcription factors, suggesting a diversity of functions. Stimulation of a diverse array of cell surface receptors, including antigen engagement of the B-cell receptor (BCR), leads to PH-mediated membrane translocation of Btk and subsequent phosphorylation by Src kinase and activation. Btk plays an important role in the life cycle of B-cells including their development, differentiation, proliferation, survival, and apoptosis. Mutations in Btk cause the primary immunodeficiency disease, X-linked agammaglobulinaemia (XLA) in humans. 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 1907130254 394 VVAVYPFVARSTHELSLQAGQPVTILEAQDkkgNPEWSLVEANGQRGYVPSNFL 447
Cdd:cd11906     3 VVALYDYTPMNAQDLQLRKGEEYVILEESN---LPWWRARDKNGREGYIPSNYV 53

Src homology 3 domain of Blk Protein Tyrosine Kinase; Blk is a member of the Src subfamily of proteins, which are cytoplasmic (or non-receptor) PTKs. It is expressed specifically in B-cells and is involved in pre-BCR (B-cell receptor) signaling. 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.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*...
gi 1907130254 394 VVAVYPFVARSTHELSLQAGQPVTILeaqdkKGNPEWSLVEA--NGQRGYVPSNFLAR 449
Cdd:cd12009     2 VIAQYDFVPSNERDLQLKKGEKLQVL-----KSDGEWWLAKSltTGKEGYIPSNYVAR 54

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        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1907130254 396 AVYPFVARSTHELSLQAGQPVTILEAQdkKGNPEWSLVEANGQRGYVPSNFLAR 449
Cdd:cd11987     4 ALYPFEARSHDEITIQPGDIVMVDESQ--TGEPGWLGGELKGKTGWFPANYAEK 55

N-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 N-terminal SH3 domain of the related protein GRB2 binds to Sos and Sos-derived proline-rich peptides. 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 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILEAQDkkgNPEWSLVEANGQRGYVPSNFL 447
Cdd:cd11948     1 EAVALYSFQATESDELPFQKGDILKILNMED---DQNWYKAELQGREGYIPKNYI 52

Src Homology 3 domain of Tec (Tyrosine kinase expressed in hepatocellular carcinoma); Tec is a cytoplasmic (or nonreceptor) tyr kinase containing Src homology protein interaction domains (SH3, SH2) N-terminal to the catalytic tyr kinase domain. It also contains an N-terminal pleckstrin homology (PH) domain, which binds the products of PI3K and allows membrane recruitment and activation, and the Tec homology (TH) domain, which contains proline-rich and zinc-binding regions. It is more widely-expressed than other Tec subfamily kinases. Tec is found in endothelial cells, both B- and T-cells, and a variety of myeloid cells including mast cells, erythroid cells, platelets, macrophages and neutrophils. Tec is a key component of T-cell receptor (TCR) signaling, and is important in TCR-stimulated proliferation, IL-2 production and phospholipase C-gamma1 activation. 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 1907130254 394 VVAVYPFVARSTHELSLQAGQPVTILEAQDKKGnpeWSLVEANGQRGYVPSNFL 447
Cdd:cd11905     3 VVAMYDFQPTEPHDLRLETGEEYVILEKNDVHW---WKARDKYGKEGYIPSNYV 53

N-terminal Src homology 3 domain of GRB2-related adaptor protein 2; GRAP2 is also called GADS (GRB2-related adapter downstream of Shc), GrpL, GRB2L, Mona, or GRID (Grb2-related protein with insert domain). It is expressed specifically in the hematopoietic system. It 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. It also have roles in antigen-receptor and tyrosine kinase mediated signaling. GRAP2 is unique from other GRB2-like adaptor proteins in that it can be regulated by caspase cleavage. It contains an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. The N-terminal SH3 domain of the related protein GRB2 binds to Sos and Sos-derived proline-rich peptides. 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 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILEAQDkkgnpEWSLVEANGQRGYVPSNFLAR 449
Cdd:cd11947     1 EARGKFDFTASGEDELSFKKGDVLKILSSDD-----IWFKAELNGEEGYVPKNFVDI 52

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

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1907130254 394 VVAVYPFVARSTHELSLQAGQPVTILeaqdKKGNPEWSLVEANGQRGYVPSNFLA 448
Cdd:cd11806     2 YVAIADFVATDDSQLSFESGDKLLVL----RKPSVDWWWAEHNGCCGYIPASHLH 52

The Bin/Amphiphysin/Rvs (BAR) domain of Saccharomyces cerevisiae Reduced viability upon starvation protein 161 and similar proteins; BAR domains are dimerization, lipid binding and curvature sensing modules found in many different proteins with diverse functions. This subfamily is composed of fungal proteins with similarity to Saccharomyces cerevisiae Reduced viability upon starvation protein 161 (Rvs161p) and Schizosaccharomyces pombe Hob3 (homolog of Bin3). S. cerevisiae Rvs161p plays a role in regulating cell polarity, actin cytoskeleton polarization, vesicle trafficking, endocytosis, bud formation, and the mating response. It forms a heterodimer with another BAR domain protein Rvs167p. Rvs161p and Rvs167p share common functions but are not interchangeable. Their BAR domains cannot be replaced with each other and the overexpression of one cannot suppress the mutant phenotypes of the other. S. pombe Hob3 is important in regulating filamentous actin localization and may be required in activating Cdc42 and recruiting it to cell division sites. BAR domains form dimers that bind to membranes, induce membrane bending and curvature, and may also be involved in protein-protein interactions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1907130254  44 AGLVSRTEDKEFDDLEERFQWVSLCVKELRNNVVDFMGNL-----------EVFLSFRPHERSLDiPGGPAEQYCSLARD 112
Cdd:cd07591     2 TGQVERTVDREFEFEERRYRTMEKASTKLQKEAKGYLDSLraltssqariaETISSFYGDAGDKD-GAMLSQEYKQAVEE 80

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1907130254 113 LQLHAFLQFKQRLRSLVWQPLCSLARALAGPQNLIKKRLDKLLDFDRVE---EKLLD--------VGSVTWEEEAARHEY 181
Cdd:cd07591    81 LDAETVKELDGPYRQTVLDPIGRFNSYFPEINEAIKKRNHKLLDYDAARakvRKLIDkpsedptkLPRAEKELDEAKEVY 160

                         170       180       190
                  ....*....|....*....|....*....|...
gi 1907130254 182 QALNSLLVAELPQFNQLVMQWLGQILCTFVVLQ 214
Cdd:cd07591   161 ETLNDQLKTELPQLVDLRIPYLDPSFEAFVKIQ 193

Src Homology 3 domain of Epidermal growth factor receptor kinase substrate 8 and similar proteins; This group is composed of Eps8 and Eps8-like proteins including Eps8-like 1-3, among others. These proteins contain N-terminal Phosphotyrosine-binding (PTB), central SH3, and C-terminal effector domains. Eps8 binds either Abi1 (also called E3b1) or Rab5 GTPase activating protein RN-tre through its SH3 domain. With Abi1 and Sos1, it becomes part of a trimeric complex that is required to activate Rac. Together with RN-tre, it inhibits the internalization of EGFR. The SH3 domains of Eps8 and similar proteins recognize peptides containing a PxxDY motif, instead of the classical PxxP motif. SH3 domains are protein interaction domains that usually 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 1907130254 394 VVAVYPFVARSTHELSLQAGQPVTILEaqDKKgnpEWSLVE-ANGQRGYVPSNFL 447
Cdd:cd11764     2 VRVLYDFTARNSKELSVLKGEYLEVLD--DSR---QWWKVRnSRGQVGYVPHNIL 51

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        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILEAQDKkgnpEWSLVEANGQRGYVPSNF 446
Cdd:cd11823     1 RCKALYSYTANREDELSLQPGDIIEVHEKQDD----GWWLGELNGKKGIFPATY 50

C-terminal (or second) Src homology 3 domain of VAV proteins; VAV proteins function both as cytoplasmic guanine nucleotide exchange factors (GEFs) for Rho GTPases and scaffold proteins and they play important roles in cell signaling by coupling cell surface receptors to various effector functions. They play key roles in processes that require cytoskeletal reorganization including immune synapse formation, phagocytosis, cell spreading, and platelet aggregation, among others. Vertebrates have three VAV proteins (VAV1, VAV2, and VAV3). VAV proteins contain several domains that enable their function: N-terminal calponin homology (CH), acidic, RhoGEF (also called Dbl-homologous or DH), Pleckstrin Homology (PH), C1 (zinc finger), SH2, and two SH3 domains. The SH3 domain of VAV is involved in the localization of proteins to specific sites within the cell, by interacting with proline-rich sequences within target proteins. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1907130254 395 VAVYPFVARSTHELSLQAGQPVTILeaqDKKGNPEWSLVEANGQRGYVPSNFL 447
Cdd:cd11830     3 KARYDFCARDMRELSLKEGDVVKIY---NKKGQQGWWRGEINGRIGWFPSTYV 52

Src homology 3 domain of the Protein Tyrosine Kinase, Abelson kinase; Abl (or c-Abl) is a ubiquitously-expressed cytoplasmic (or nonreceptor) PTK that contains SH3, SH2, and tyr kinase domains in its N-terminal region, as well as nuclear localization motifs, a putative DNA-binding domain, and F- and G-actin binding domains in its C-terminal tail. It also contains a short autoinhibitory cap region in its N-terminus. Abl function depends on its subcellular localization. In the cytoplasm, Abl plays a role in cell proliferation and survival. In response to DNA damage or oxidative stress, Abl is transported to the nucleus where it induces apoptosis. In chronic myelogenous leukemia (CML) patients, an aberrant translocation results in the replacement of the first exon of Abl with the BCR (breakpoint cluster region) gene. The resulting BCR-Abl fusion protein is constitutively active and associates into tetramers, resulting in a hyperactive kinase sending a continuous signal. This leads to uncontrolled proliferation, morphological transformation and anti-apoptotic effects. BCR-Abl is the target of selective inhibitors, such as imatinib (Gleevec), used in the treatment of CML. Abl2, also known as ARG (Abelson-related gene), is thought to play a cooperative role with Abl in the proper development of the nervous system. The Tel-ARG fusion protein, resulting from reciprocal translocation between chromosomes 1 and 12, is associated with acute myeloid leukemia (AML). SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 1907130254 395 VAVYPFVARSTHELSLQAGQPVTILEAQdkkGNPEWSLVEA--NGQRGYVPSNFLAR 449
Cdd:cd11850     3 VALYDFVASGENQLSIKKGEQLRVLGYN---KNGEWCEAESksTGGQGWVPSNYITP 56

Third Src Homology 3 domain of Nck1 adaptor protein; Nck1 (also called Nckalpha) plays a crucial role in connecting signaling pathways of tyrosine kinase receptors and important effectors in actin dynamics and cytoskeletal remodeling. It binds and activates RasGAP, resulting in the downregulation of Ras. It is also involved in the signaling of endothilin-mediated inhibition of cell migration. 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, which show partly overlapping functions but also bind distinct targets. The third SH3 domain of Nck appears to prefer ligands with a PxAPxR 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        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1907130254 394 VVAVYPFVARSTHELSLQAGQPVTILEAQDKkgNPE-WSLVEANGQRGYVPSNFL 447
Cdd:cd11904     3 VQALYPFSSSNDEELNFEKGEVMDVIEKPEN--DPEwWKCRKANGQVGLVPKNYV 55

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.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILEAQDkkgnPEWSLVEANGQRGYVPSNFL 447
Cdd:cd11964     2 KVRAIYDFEAAEDNELTFKAGDIITILDDSD----PNWWKGETPQGTGLFPSNFV 52

First Src homology 3 domain of the RhoGEF kinase, Kalirin; Kalirin, also called Duo, Duet, or TRAD, is a large neuronal dual Rho guanine nucleotide exchange factor (RhoGEF) that activates Rac1, RhoA, and RhoG using two RhoGEF domains. Kalirin exists in many isoforms generated by alternative splicing and the use of multiple promoters; the major isoforms are kalirin-7, -9, and -12, which differ at their C-terminal ends. Kalirin-12, the longest isoform, contains an N-terminal Sec14p domain, spectrin-like repeats, two RhoGEF domains, two SH3 domains, as well as Ig, FNIII, and kinase domains at the C-terminal end. Kalirin-7 contains only a single RhoGEF domain and does not contain an SH3 domain. Kalirin, through its many isoforms, interacts with many different proteins and is able to localize to different locations within the cell. It influences neurite initiation, axon growth, dendritic morphogenesis, vesicle trafficking, neuronal maintenance, and neurodegeneration. 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 1907130254 395 VAVYPFVARSTHELSLQAGQPVTILEAQDKKgnPEWSLVEANG------QRGYVPSNFLA 448
Cdd:cd11852     4 VVIEDFEATSSQELTVSKGQTVEVLERPSSR--PDWCLVRTLEqdnsppQEGLVPSSILC 61

Src homology 3 domain of Lck Protein Tyrosine Kinase; Lck is a member of the Src subfamily of proteins, which are cytoplasmic (or non-receptor) PTKs. Lck is expressed in T-cells and natural killer cells. It plays a critical role in T-cell maturation, activation, and T-cell receptor (TCR) signaling. Lck phosphorylates ITAM (immunoreceptor tyr activation motif) sequences on several subunits of TCRs, leading to the activation of different second messenger cascades. Phosphorylated ITAMs serve as binding sites for other signaling factor such as Syk and ZAP-70, leading to their activation and propagation of downstream events. In addition, Lck regulates drug-induced apoptosis by interfering with the mitochondrial death pathway. The apototic role of Lck is independent of its primary function in T-cell signaling. 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.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1907130254 393 QVVAVYPFVARSTHELSLQAGQPVTILEAqdkkgNPEWSLVEA--NGQRGYVPSNFLAR 449
Cdd:cd12005     1 LVVALYSYEPSHDGDLGFEKGEKLRILEQ-----SGEWWKAQSltTGQEGFIPFNFVAK 54

Src Homology 3 (SH3) domain of Inhibitor of ASPP protein (iASPP); iASPP, also called RelA-associated inhibitor (RAI), is an oncoprotein that inhibits the apoptotic transactivation potential of p53. It is upregulated in human breast cancers expressing wild-type p53, in acute leukemias regardless of the p53 mutation status, as well as in ovarian cancer where it is associated with poor patient outcome and chemoresistance. iASPP is also a binding partner and negative regulator of p65RelA, which promotes cell proliferation and inhibits apoptosis; p65RelA has the opposite effect on cell growth compared to the p53 family. It contains a proline-rich region, four ankyrin (ANK) repeats, and an SH3 domain at its C-terminal half. The SH3 domain and the ANK repeats of iASPP contribute to the p53 binding site; they bind to the DNA binding domain of p53. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1907130254 394 VVAVYPFVARSTHELSLQAGQPVTILEaQDKKGNpEWSLVEANGQRGYVPSNFL 447
Cdd:cd11952     3 VYALWDYSAEFPDELSFKEGDMVTVLR-KDGEGT-DWWWASLCGREGYVPRNYF 54

Src homology 3 domain of Brk (Breast tumor kinase) Protein Tyrosine Kinase (PTK), also called PTK6; Brk is a cytoplasmic (or non-receptor) PTK with limited homology to Src kinases. It has been found to be overexpressed in a majority of breast tumors. It plays roles in normal cell differentiation, proliferation, survival, migration, and cell cycle progression. Brk substrates include RNA-binding proteins (SLM-1/2, Sam68), transcription factors (STAT3/5), and signaling molecules (Akt, paxillin, IRS-4). Src kinases in general 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). However, Brk lacks the N-terminal myristoylation site. 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.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1907130254 395 VAVYPFVARSTHELSLQAGQPVTILEAQDkkgnpEW---SLVEANGQ---RGYVPSNFLAR 449
Cdd:cd11847     3 KALWDFKARGDEELSFQAGDQFRIAERSG-----DWwtaLKLDRAGGvvaQGFVPNNYLAR 58

First 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 first 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 1907130254 396 AVYPFVARSTHELSLQAGQPVTILEAQDKKGnpeWSLVEANGQR-GYVPSNFL 447
Cdd:cd11912     4 VLYDYTASGDDEVSISEGEEVTVLEPDDGSG---WTKVRNGSGEeGLVPTSYI 53

Fourth Src homology 3 domain of ADAM-binding protein Eve-1; Eve-1, also called SH3 domain-containing protein 19 (SH3D19) or EEN-binding protein (EBP), exists in multiple alternatively spliced isoforms. The longest isoform contains five SH3 domain in the C-terminal region and seven proline-rich motifs in the N-terminal region. It is abundantly expressed in skeletal muscle and heart, and may be involved in regulating the activity of ADAMs (A disintegrin and metalloproteases). Eve-1 interacts with EEN, an endophilin involved in endocytosis and may be the target of the MLL-EEN fusion protein that is implicated in leukemogenesis. 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 1907130254 394 VVAVYPFVARSTHELSLQAGQPVTILEAQDKkgnpEWSLVEANGQRGYVPSNF 446
Cdd:cd11817     2 AVALYDFTGETEEDLSFQRGDRILVTEHLDA----EWSRGRLNGREGIFPRAF 50