The phosphoinositide binding Phox Homology domain of the p47phox subunit of NADPH oxidase; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions such as cell signaling, vesicular trafficking, protein sorting, and lipid modification, among others. p47phox is a cytosolic subunit of the phagocytic NADPH oxidase complex (also called Nox2 or gp91phox), which plays a key role in the ability of phagocytes to defend against bacterial infections. NADPH oxidase catalyzes the transfer of electrons from NADPH to oxygen during phagocytosis forming superoxide and reactive oxygen species. p47phox is required for activation of NADH oxidase and plays a role in translocation. It contains an N-terminal PX domain, two Src Homology 3 (SH3) domains, and a C-terminal domain that contains PxxP motifs for binding SH3 domains. The PX domain of p47phox is unique in that it contains two distinct basic pockets on the membrane-binding surface: one preferentially binds phosphatidylinositol-3,4-bisphosphate [PI(3,4)P2] and is analogous to the PI3P-binding pocket of p40phox, while the other binds anionic phospholipids such as phosphatidic acid or phosphatidylserine. Simultaneous binding in the two pockets results in increased membrane affinity. The PX domain of p47phox is also involved in protein-protein interaction.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74189725   6 IRHIALLGFEKRFIPSQHYVYMFLVKWQDLSEKVVYRKFTEIYEFHKMLKEMFPIEAGEIHTENRVIPHLPAPRWFDGQR 85
Cdd:cd06887   1 IRHIALLGFEKRFVPSQHYVYMFLVKWQDLSEKLVYRRFTEIYEFHKTLKEMFPIEAGDINKENRIIPHLPAPKWFDGQR 80

                        90       100       110
                ....*....|....*....|....*....|....*...
gi 74189725  86 AAESRQGTLTEYFNGLMGLPVKISRCPHLLDFFKVRPD 123
Cdd:cd06887  81 AAENRQGTLTEYCSTLLSLPPKISRCPHVLDFFKVRPD 118

First or N-terminal Src homology 3 domain of the p47phox subunit of NADPH oxidase, also called Neutrophil Cytosolic Factor 1; p47phox, or NCF1, is a cytosolic subunit of the phagocytic NADPH oxidase complex (also called Nox2 or gp91phox), which plays a key role in the ability of phagocytes to defend against bacterial infections. NADPH oxidase catalyzes the transfer of electrons from NADPH to oxygen during phagocytosis forming superoxide and reactive oxygen species. p47phox is required for activation of NADH oxidase and plays a role in translocation. It contains an N-terminal Phox homology (PX) domain, tandem SH3 domains (N-SH3 and C-SH3), a polybasic/autoinhibitory region, and a C-terminal proline-rich region (PRR). This model characterizes the first SH3 domain (or N-SH3) of p47phox. In its inactive state, the tandem SH3 domains interact intramolecularly with the autoinhibitory region; upon activation, the tandem SH3 domains are exposed through a conformational change, resulting in their binding to the PRR of p22phox and the activation of NADPH oxidase. 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 74189725 160 TYRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLEP 212
Cdd:cd12021   1 TYRAIADYEKSSKSEMALKTGDVVEVVEKSENGWWFCQLKAKRGWVPASYLEP 53

NADPH oxidase subunit p47Phox, C terminal domain; The C terminal domain of the phagocyte NADPH oxidase subunit p47Phox contains conserved PxxP motifs that allow binding to SH3 domains, with subsequent activation of the NADPH oxidase, and generation of superoxide, which plays a crucial role in host defence against microbial infection.

                          10        20        30
                  ....*....|....*....|....*....|.
gi 74189725   360 KPQPAVPPRPSSDLILHRCTESTKRKLTSAV 390
Cdd:pfam08944   2 KPQPAVPPRPSPDLILERCSESTKRKLSSAV 32

The phosphoinositide binding Phox Homology domain of the p47phox subunit of NADPH oxidase; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions such as cell signaling, vesicular trafficking, protein sorting, and lipid modification, among others. p47phox is a cytosolic subunit of the phagocytic NADPH oxidase complex (also called Nox2 or gp91phox), which plays a key role in the ability of phagocytes to defend against bacterial infections. NADPH oxidase catalyzes the transfer of electrons from NADPH to oxygen during phagocytosis forming superoxide and reactive oxygen species. p47phox is required for activation of NADH oxidase and plays a role in translocation. It contains an N-terminal PX domain, two Src Homology 3 (SH3) domains, and a C-terminal domain that contains PxxP motifs for binding SH3 domains. The PX domain of p47phox is unique in that it contains two distinct basic pockets on the membrane-binding surface: one preferentially binds phosphatidylinositol-3,4-bisphosphate [PI(3,4)P2] and is analogous to the PI3P-binding pocket of p40phox, while the other binds anionic phospholipids such as phosphatidic acid or phosphatidylserine. Simultaneous binding in the two pockets results in increased membrane affinity. The PX domain of p47phox is also involved in protein-protein interaction.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74189725   6 IRHIALLGFEKRFIPSQHYVYMFLVKWQDLSEKVVYRKFTEIYEFHKMLKEMFPIEAGEIHTENRVIPHLPAPRWFDGQR 85
Cdd:cd06887   1 IRHIALLGFEKRFVPSQHYVYMFLVKWQDLSEKLVYRRFTEIYEFHKTLKEMFPIEAGDINKENRIIPHLPAPKWFDGQR 80

                        90       100       110
                ....*....|....*....|....*....|....*...
gi 74189725  86 AAESRQGTLTEYFNGLMGLPVKISRCPHLLDFFKVRPD 123
Cdd:cd06887  81 AAENRQGTLTEYCSTLLSLPPKISRCPHVLDFFKVRPD 118

First or N-terminal Src homology 3 domain of the p47phox subunit of NADPH oxidase, also called Neutrophil Cytosolic Factor 1; p47phox, or NCF1, is a cytosolic subunit of the phagocytic NADPH oxidase complex (also called Nox2 or gp91phox), which plays a key role in the ability of phagocytes to defend against bacterial infections. NADPH oxidase catalyzes the transfer of electrons from NADPH to oxygen during phagocytosis forming superoxide and reactive oxygen species. p47phox is required for activation of NADH oxidase and plays a role in translocation. It contains an N-terminal Phox homology (PX) domain, tandem SH3 domains (N-SH3 and C-SH3), a polybasic/autoinhibitory region, and a C-terminal proline-rich region (PRR). This model characterizes the first SH3 domain (or N-SH3) of p47phox. In its inactive state, the tandem SH3 domains interact intramolecularly with the autoinhibitory region; upon activation, the tandem SH3 domains are exposed through a conformational change, resulting in their binding to the PRR of p22phox and the activation of NADPH oxidase. 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 74189725 160 TYRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLEP 212
Cdd:cd12021   1 TYRAIADYEKSSKSEMALKTGDVVEVVEKSENGWWFCQLKAKRGWVPASYLEP 53

PX domain; PX domains bind to phosphoinositides.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74189725    30 VKWQDLSEKVVYRKFTEIYEFHKMLKEMFPieageihteNRVIPHLPAPRWFDG--QRAAESRQGTLTEYFNGLMGLPVk 107
Cdd:pfam00787   1 LPTFSLEEWSVRRRYSDFVELHKKLLRKFP---------SVIIPPLPPKRWLGRynEEFIEKRRKGLEQYLQRLLQHPE- 70

                          90
                  ....*....|....
gi 74189725   108 ISRCPHLLDFFKVR 121
Cdd:pfam00787  71 LRNSEVLLEFLESD 84

NADPH oxidase subunit p47Phox, C terminal domain; The C terminal domain of the phagocyte NADPH oxidase subunit p47Phox contains conserved PxxP motifs that allow binding to SH3 domains, with subsequent activation of the NADPH oxidase, and generation of superoxide, which plays a crucial role in host defence against microbial infection.

                          10        20        30
                  ....*....|....*....|....*....|.
gi 74189725   360 KPQPAVPPRPSSDLILHRCTESTKRKLTSAV 390
Cdd:pfam08944   2 KPQPAVPPRPSPDLILERCSESTKRKLSSAV 32

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 74189725    228 GEPYVTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGD-ITGYFPSMYLQ 281
Cdd:smart00326   2 GPQVRALYDYTAQDPDELSFKKGDIITVLEKSDDGWWKGRLGRgKEGLFPSNYVE 56

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
                  ....*....|....*....|....*....|....*....|....*..
gi 74189725   232 VTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVR-KGDITGYFPS 277
Cdd:pfam00018   1 VALYDYTAQEPDELSFKKGDIIIVLEKSEDGWWKGRnKGGKEGLIPS 47

Uncharacterized conserved protein YraI [Function unknown];

                        10        20        30
                ....*....|....*....|....*....|....*....
gi 74189725 176 TVATGDVVDVVEKSESGWWfCQMKT--KRGWVPASYLEP 212
Cdd:COG4991  46 TLPAGATVTVLGCTSGGGW-CKVSYggQRGWVSARYLQV 83

The phosphoinositide binding Phox Homology domain of the p47phox subunit of NADPH oxidase; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions such as cell signaling, vesicular trafficking, protein sorting, and lipid modification, among others. p47phox is a cytosolic subunit of the phagocytic NADPH oxidase complex (also called Nox2 or gp91phox), which plays a key role in the ability of phagocytes to defend against bacterial infections. NADPH oxidase catalyzes the transfer of electrons from NADPH to oxygen during phagocytosis forming superoxide and reactive oxygen species. p47phox is required for activation of NADH oxidase and plays a role in translocation. It contains an N-terminal PX domain, two Src Homology 3 (SH3) domains, and a C-terminal domain that contains PxxP motifs for binding SH3 domains. The PX domain of p47phox is unique in that it contains two distinct basic pockets on the membrane-binding surface: one preferentially binds phosphatidylinositol-3,4-bisphosphate [PI(3,4)P2] and is analogous to the PI3P-binding pocket of p40phox, while the other binds anionic phospholipids such as phosphatidic acid or phosphatidylserine. Simultaneous binding in the two pockets results in increased membrane affinity. The PX domain of p47phox is also involved in protein-protein interaction.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74189725   6 IRHIALLGFEKRFIPSQHYVYMFLVKWQDLSEKVVYRKFTEIYEFHKMLKEMFPIEAGEIHTENRVIPHLPAPRWFDGQR 85
Cdd:cd06887   1 IRHIALLGFEKRFVPSQHYVYMFLVKWQDLSEKLVYRRFTEIYEFHKTLKEMFPIEAGDINKENRIIPHLPAPKWFDGQR 80

                        90       100       110
                ....*....|....*....|....*....|....*...
gi 74189725  86 AAESRQGTLTEYFNGLMGLPVKISRCPHLLDFFKVRPD 123
Cdd:cd06887  81 AAENRQGTLTEYCSTLLSLPPKISRCPHVLDFFKVRPD 118

First or N-terminal Src homology 3 domain of the p47phox subunit of NADPH oxidase, also called Neutrophil Cytosolic Factor 1; p47phox, or NCF1, is a cytosolic subunit of the phagocytic NADPH oxidase complex (also called Nox2 or gp91phox), which plays a key role in the ability of phagocytes to defend against bacterial infections. NADPH oxidase catalyzes the transfer of electrons from NADPH to oxygen during phagocytosis forming superoxide and reactive oxygen species. p47phox is required for activation of NADH oxidase and plays a role in translocation. It contains an N-terminal Phox homology (PX) domain, tandem SH3 domains (N-SH3 and C-SH3), a polybasic/autoinhibitory region, and a C-terminal proline-rich region (PRR). This model characterizes the first SH3 domain (or N-SH3) of p47phox. In its inactive state, the tandem SH3 domains interact intramolecularly with the autoinhibitory region; upon activation, the tandem SH3 domains are exposed through a conformational change, resulting in their binding to the PRR of p22phox and the activation of NADPH oxidase. 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 74189725 160 TYRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLEP 212
Cdd:cd12021   1 TYRAIADYEKSSKSEMALKTGDVVEVVEKSENGWWFCQLKAKRGWVPASYLEP 53

The phosphoinositide binding Phox Homology domain of Five SH protein; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions such as cell signaling, vesicular trafficking, protein sorting, and lipid modification, among others. Five SH (FISH), also called Tks5, is a scaffolding protein and Src substrate that is localized in podosomes, which are electron-dense structures found in Src-transformed fibroblasts, osteoclasts, macrophages, and some invasive cancer cells. FISH contains an N-terminal PX domain and five Src homology 3 (SH3) domains. FISH binds and regulates some members of the ADAMs family of transmembrane metalloproteases, which function as sheddases and mediators of cell and matrix interactions. It is required for podosome formation, degradation of the extracellular matrix, and cancer cell invasion. This subfamily also includes proteins with a different number of SH3 domains than FISH, such as Tks4, which contains four SH3 domains instead of five. The Tks4 adaptor protein is required for the formation of functional podosomes. It has overlapping, but not identical, functions as FISH. The PX domain is involved in targeting of proteins to PI-enriched membranes, and may also be involved in protein-protein interaction.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74189725  15 EKRFIPSQHYVYMFLVKWQDLSEKVVYRKFTEIYEFHKMLKEMFPIEAGEIHTENRVIPHLPAPRWF---DGQRAAESRQ 91
Cdd:cd06888  10 EKRRAPSKHYVYIINVTWSDGSSNVIYRRYSKFFDLQMQLLDKFPIEGGQKDPSQRIIPFLPGKILFrrsHIRDVAVKRL 89

                        90       100       110
                ....*....|....*....|....*....|
gi 74189725  92 GTLTEYFNGLMGLPVKISRCPHLLDFFKVR 121
Cdd:cd06888  90 KPIDEYCKALVRLPPHISQCDEVLRFFEAK 119

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

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|..
gi 74189725 161 YRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLEP 212
Cdd:cd12015   2 YVVVADYKKQQPNEISLRAGDVVDVIEKNENGWWFVSLEDEQGWVPATYLEP 53

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

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|.
gi 74189725 161 YRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLE 211
Cdd:cd12074   2 YVVVSNYEKQENSEISLQAGEVVDVIEKNESGWWFVSTAEEQGWVPATYLE 52

PX domain; PX domains bind to phosphoinositides.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 74189725    30 VKWQDLSEKVVYRKFTEIYEFHKMLKEMFPieageihteNRVIPHLPAPRWFDG--QRAAESRQGTLTEYFNGLMGLPVk 107
Cdd:pfam00787   1 LPTFSLEEWSVRRRYSDFVELHKKLLRKFP---------SVIIPPLPPKRWLGRynEEFIEKRRKGLEQYLQRLLQHPE- 70

                          90
                  ....*....|....
gi 74189725   108 ISRCPHLLDFFKVR 121
Cdd:pfam00787  71 LRNSEVLLEFLESD 84

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

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|.
gi 74189725 161 YRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLE 211
Cdd:cd12075   3 YVVVANYQKQESSEISLYVGQVVDIIEKNESGWWFVSTADEQGWVPATCLE 53

NADPH oxidase subunit p47Phox, C terminal domain; The C terminal domain of the phagocyte NADPH oxidase subunit p47Phox contains conserved PxxP motifs that allow binding to SH3 domains, with subsequent activation of the NADPH oxidase, and generation of superoxide, which plays a crucial role in host defence against microbial infection.

                          10        20        30
                  ....*....|....*....|....*....|.
gi 74189725   360 KPQPAVPPRPSSDLILHRCTESTKRKLTSAV 390
Cdd:pfam08944   2 KPQPAVPPRPSPDLILERCSESTKRKLSSAV 32

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 74189725    159 QTYRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKT-KRGWVPASYLE 211
Cdd:smart00326   3 PQVRALYDYTAQDPDELSFKKGDIITVLEKSDDGWWKGRLGRgKEGLFPSNYVE 56

Second or C-terminal Src homology 3 domain of NADPH oxidase (Nox) Organizing protein 1; Nox Organizing protein 1 (NoxO1) is a critical regulator of enzyme kinetics of the nonphagocytic NADPH oxidase Nox1, which catalyzes the transfer of electrons from NADPH to molecular oxygen to form superoxide. Nox1 is expressed in colon, stomach, uterus, prostate, and vascular smooth muscle cells. NoxO1 is involved in targeting activator subunits (such as NoxA1) to Nox1. It is co-localized with Nox1 in the membranes of resting cells and directs the subcellular localization of Nox1. NoxO1 contains an N-terminal Phox homology (PX) domain, tandem SH3 domains (N-SH3 and C-SH3), and a C-terminal proline-rich region (PRR). This model characterizes the second SH3 domain (or C-SH3) of NoxO1. The tandem SH3 domains of NoxO1 interact with the PRR of p22phox, which also complexes with Nox1. 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 74189725 231 YVTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQ 281
Cdd:cd12024   2 YYATRAYEAQKEDELSVPAGVVVEVLQKSDNGWWLIRYNGRAGYVPSMYLQ 52

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
                ....*....|....*....|....*....|....*....|....*....|.
gi 74189725 160 TYRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQ-MKTKRGWVPASY 209
Cdd:cd00174   1 YARALYDYEAQDDDELSFKKGDIITVLEKDDDGWWEGElNGGREGLFPANY 51

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 74189725    228 GEPYVTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGD-ITGYFPSMYLQ 281
Cdd:smart00326   2 GPQVRALYDYTAQDPDELSFKKGDIITVLEKSDDGWWKGRLGRgKEGLFPSNYVE 56

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
                  ....*....|....*....|....*....|....*....|....*..
gi 74189725   162 RAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKT-KRGWVPA 207
Cdd:pfam00018   1 VALYDYTAQEPDELSFKKGDIIIVLEKSEDGWWKGRNKGgKEGLIPS 47

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

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....
gi 74189725 229 EPYVTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQK 282
Cdd:cd12076   1 EKYTVIYPYTARDQDEINLEKGAVVEVIQKNLEGWWKIRYQGKEGWAPASYLKK 54

Second or C-terminal Src homology 3 domain of NADPH oxidase (Nox) Organizing protein 1; Nox Organizing protein 1 (NoxO1) is a critical regulator of enzyme kinetics of the nonphagocytic NADPH oxidase Nox1, which catalyzes the transfer of electrons from NADPH to molecular oxygen to form superoxide. Nox1 is expressed in colon, stomach, uterus, prostate, and vascular smooth muscle cells. NoxO1 is involved in targeting activator subunits (such as NoxA1) to Nox1. It is co-localized with Nox1 in the membranes of resting cells and directs the subcellular localization of Nox1. NoxO1 contains an N-terminal Phox homology (PX) domain, tandem SH3 domains (N-SH3 and C-SH3), and a C-terminal proline-rich region (PRR). This model characterizes the second SH3 domain (or C-SH3) of NoxO1. The tandem SH3 domains of NoxO1 interact with the PRR of p22phox, which also complexes with Nox1. 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 74189725 161 YRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLEP 212
Cdd:cd12024   2 YYATRAYEAQKEDELSVPAGVVVEVLQKSDNGWWLIRYNGRAGYVPSMYLQP 53

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

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                ....*....|....*....|....*....|....*....|....*....|.
gi 74189725 161 YRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLE 211
Cdd:cd12017   2 YFTIGEFQATIQDGISFQKGQKVEVIDKNPSGWWYVKIDGKEGWAPSSYIE 52

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.

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                  ....*....|....*....|....*....|....*....|....*....|...
gi 74189725   161 YRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLEPL 213
Cdd:pfam07653   2 GRVIFDYVGTDKNGLTLKKGDVVKVLGKDNDGWWEGETGGRVGLVPSTAVEEI 54

Variant SH3 domain;

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                  ....*....|....*....|....*....|....*....|....*...
gi 74189725   234 IKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQ 281
Cdd:pfam14604   2 LYPYEPKDDDELSLQRGDVITVIEESEDGWWEGINTGRTGLVPANYVE 49

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.

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                ....*....|....*....|....*....|....*....|....*....|
gi 74189725 232 VTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQ 281
Cdd:cd11823   3 KALYSYTANREDELSLQPGDIIEVHEKQDDGWWLGELNGKKGIFPATYVE 52

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

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                ....*....|....*....|....*....|....*....|....*....|...
gi 74189725 159 QTYRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLE 211
Cdd:cd12077   1 EKYVTVQPYTSQGKDEIGFEKGVTVEVIQKNLEGWWYIRYLGKEGWAPASYLK 53

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.

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                ....*....|....*....|....*....|....*....|....*....|
gi 74189725 162 RAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLE 211
Cdd:cd11823   3 KALYSYTANREDELSLQPGDIIEVHEKQDDGWWLGELNGKKGIFPATYVE 52

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

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 74189725 159 QTYRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLE 211
Cdd:cd12016   1 EKYITTQAYKAENEDEIGFETGVVVEVIQKNLDGWWKIRYQGKEGWAPATYLK 53

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

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                ....*....|....*....|....*....|....*....|....*....|.
gi 74189725 161 YRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLE 211
Cdd:cd12079   3 YYTIAEFQSCISDGISFRGGQKAEVIEKNSGGWWYVQIGEKEGWAPSSYID 53

Src homology 3 domain of DBL's Big Sister (DBS), a guanine nucleotide exchange factor; DBS, also called MCF2L (MCF2-transforming sequence-like protein) or OST, is a Rho GTPase guanine nucleotide exchange factor (RhoGEF), facilitating the exchange of GDP and GTP. It was originally isolated from a cDNA screen for sequences that cause malignant growth. It plays roles in regulating clathrin-mediated endocytosis and cell migration through its activation of Rac1 and Cdc42. Depending on cell type, DBS can also activate RhoA and RhoG. DBS contains a Sec14-like domain, spectrin-like repeats, a RhoGEF [or Dbl homology (DH)] domain, a Pleckstrin homology (PH) domain, and an 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 74189725 161 YRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKT--KRGWVPASYLEP 212
Cdd:cd11857   2 YTVVADYEKGGPDDLTVKSGDLVQLIHEGDEGQWLVKNLStrKEGWVPAANLQP 55

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

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                ....*....|....*....|....*....|....*....|....*....|..
gi 74189725 231 YVTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQK 282
Cdd:cd12017   2 YFTIGEFQATIQDGISFQKGQKVEVIDKNPSGWWYVKIDGKEGWAPSSYIEK 53

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

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                ....*....|....*....|....*....|....*....|....*....|..
gi 74189725 231 YVTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQK 282
Cdd:cd12015   2 YVVVADYKKQQPNEISLRAGDVVDVIEKNENGWWFVSLEDEQGWVPATYLEP 53

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

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*
gi 74189725 237 YAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQ 281
Cdd:cd11874   8 YTPQNEDELELKVGDTIEVLGEVEEGWWEGKLNGKVGVFPSNFVK 52

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

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*.
gi 74189725 237 YAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQK 282
Cdd:cd11766   8 YEAQREDELSLRKGDRVLVLEKSSDGWWRGECNGQVGWFPSNYVTE 53

First Src homology 3 domain (or SH3A) of Intersectin-2; Intersectin-2 (ITSN2) is an adaptor protein that functions in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. It plays a role in clathrin-coated pit (CCP) formation. It binds to many proteins through its multidomain structure and facilitate the assembly of multimeric complexes. ITSN2 also functions as a specific GEF for Cdc42 activation in epithelial morphogenesis, and is required in mitotic spindle orientation. It exists in alternatively spliced short and long isoforms. The short isoform contains two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoform, in addition, contains RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. The first SH3 domain (or SH3A) of ITSN2 is expected to bind many protein partners, similar to ITSN1 which has been shown to bind Sos1, dynamin1/2, CIN85, c-Cbl, PI3K-C2, SHIP2, N-WASP, and CdGAP, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....*.
gi 74189725 158 LQTYRAIADYEKSSGTEMTVATGDVVDVVEKS--ESGWWFCQMKTKRGWVPASYLE 211
Cdd:cd11988   1 LVNYRALYPFEARNHDEMSFNAGDIIQVDEKTvgEPGWLYGSFQGNFGWFPCNYVE 56

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

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                ....*....|....*....|....*....|....*....|....*....|
gi 74189725 233 TIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQK 282
Cdd:cd11827   4 ALYAYDAQDTDELSFNEGDIIEILKEDPSGWWTGRLRGKEGLFPGNYVEK 53

Fourth Src homology 3 domain (or SH3D) of Intersectin; Intersectins (ITSNs) are adaptor proteins that function in exo- and endocytosis, actin cytoskeletal reorganization, and signal transduction. They are essential for initiating clathrin-coated pit formation. They bind to many proteins through their multidomain structure and facilitate the assembly of multimeric complexes. Vertebrates contain two ITSN proteins, ITSN1 and ITSN2, which exist in alternatively spliced short and long isoforms. The short isoforms contain two Eps15 homology domains (EH1 and EH2), a coiled-coil region and five SH3 domains (SH3A-E), while the long isoforms, in addition, contain RhoGEF (also called Dbl-homologous or DH), Pleckstrin homology (PH) and C2 domains. ITSN1 and ITSN2 are both widely expressed, with variations depending on tissue type and stage of development. The fourth SH3 domain (or SH3D) of ITSN1 has been shown to bind SHIP2, Numb, CdGAP, and N-WASP. 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 74189725 162 RAIADYEKSSGTEMTVATGDVVDVVEKSESGWWF--CQ---MKTKRGWVPASYLE 211
Cdd:cd11839   3 QVIAPFTATAENQLSLAVGQLVLVRKKSPSGWWEgeLQargKKRQIGWFPANYVK 57

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.

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                ....*....|....*....|....*....|....*....|....*....|
gi 74189725 166 DYEKSSGTEMTVATGDVVDVVEKSESG-WWFCQM--KTKRGWVPASYLEP 212
Cdd:cd11775   8 DFDAQSDDELTVKEGDVVYILDDKKSKdWWMVENvsTGKEGVVPASYIEI 57

Third (or C-terminal) Src Homology 3 domain of Sorbin and SH3 domain containing 2 (Sorbs2), also called Arg-binding protein 2 (ArgBP2); Sorbs2 or ArgBP2 is an adaptor protein containing one sorbin homology (SoHo) and three SH3 domains. It regulates actin-dependent processes including cell adhesion, morphology, and migration. It is expressed in many tissues and is abundant in the heart. Like vinexin, it is found in focal adhesion where it interacts with vinculin and afadin. It also localizes in epithelial cell stress fibers and in cardiac muscle cell Z-discs. Sorbs2 has been implicated to play roles in the signaling of c-Arg, Akt, and Pyk2. Other interaction partners of Sorbs2 include c-Abl, flotillin, spectrin, dynamin 1/2, synaptojanin, PTP-PEST, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

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                ....*....|....*....|....*....|....*....|....*....|....*..
gi 74189725 228 GEPYVTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWV--VRKGDITGYFPSMYLQK 282
Cdd:cd11917   4 GEPFQALYNYMPRNEDELELREGDVIDVMEKCDDGWFVgtSRRTKFFGTFPGNYVKR 60

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

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|...
gi 74189725 160 TYRAIADYEKSSGTEMTVATGDVVDVVEKSESGWWFCQMKTKRGWVPASYLEP 212
Cdd:cd11877   1 LVRAKFNFEGTNEDELSFDKGDIITVTQVVEGGWWEGTLNGKTGWFPSNYVKE 53

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

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                ....*....|....*....|....*....|....*....|....*....|..
gi 74189725 231 YVTIKAYAAVEEDEMSLSEGEAIEVIHKLLDGWWVVRKGDITGYFPSMYLQK 282
Cdd:cd11806   2 YVAIADFVATDDSQLSFESGDKLLVLRKPSVDWWWAEHNGCCGYIPASHLHQ 53