VHS, ENTH and ANTH domain superfamily; This superfamily is composed of proteins containing a VHS, CID, ENTH, or ANTH domain. The VHS domain is present in Vps27 (Vacuolar Protein Sorting), Hrs (Hepatocyte growth factor-regulated tyrosine kinase substrate) and STAM (Signal Transducing Adaptor Molecule). It is located at the N-termini of proteins involved in intracellular membrane trafficking. The CTD-Interacting Domain (CID) is present in several RNA-processing factors and binds tightly to the carboxy-terminal domain (CTD) of RNA polymerase II (RNAP II or Pol II). The epsin N-terminal homology (ENTH) domain is an evolutionarily conserved protein module found primarily in proteins that participate in clathrin-mediated endocytosis. A set of proteins previously designated as harboring an ENTH domain in fact contains a highly similar, yet unique module referred to as an AP180 N-Terminal Homology (ANTH) domain. VHS, ENTH, and ANTH domains are structurally similar and are composed of a superhelix of eight alpha helices. ENTH and ANTH (E/ANTH) domains bind both inositol phospholipids and proteins and contribute to the nucleation and formation of clathrin coats on membranes. ENTH domains also function in the development of membrane curvature through lipid remodeling during the formation of clathrin-coated vesicles. E/ANTH domain-bearing proteins have recently been shown to function with adaptor protein-1 and GGA adaptors at the Trans-Golgi Network, which suggests that E/ANTH domains are universal components of the machinery for clathrin-mediated membrane budding.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889   1 MRRVNHKDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASEVSNVL-NKGHPKVCEKLKALMVEWTDEFKNDPQLSLIS 79
Cdd:cd16999    43 MKRVNHKVPHVALQALTLLGACVSNCGKIFHLEVCSRDFATEVRAVIkNKAHPKVCEKLKALMVEWSEEFQKDPQFSLIS 122

                          90
                  ....*....|....*..
gi 1248026889  80 AMIKNLKEQGVTFPAIG 96
Cdd:cd16999   123 ATIKSLKEEGITFPPAG 139

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 1248026889 163 RKVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFVTAD 217
Cdd:cd11964     1 RKVRAIYDFEAAEDNELTFKAGDIITILDDSDPNWWKGETPQGTGLFPSNFVTAD 55

VHS (Vps27/Hrs/STAM) domain of Signal Transducing Adapter Molecule 2; Signal Transducing Adapter Molecule 2 (STAM2) is also called EAST (EGFR-Associated protein with SH3 and TAM domain) and Hbp (Hrs-binding protein). It is highly expressed in neurons, where it is localized in the nucleus. STAM (Signal Transducing Adaptor Molecule) subfamily members have at their N-termini a VHS domain, which is involved in cytokine-mediated intracellular signal transduction and has a superhelical structure similar to the structure of ARM (Armadillo) repeats, followed by a Ubiquitin-Interacting Motif (UIM) and a SH3 (Src Homology 3) domain, which is a well-established protein-protein interaction domain, and a GAT (GGA and TOM) domain. At the C-termini of most vertebrate STAMS, an Immunoreceptor Tyrosine-based Activation Motif (ITAM) is present, which mediates the binding of HRS (hepatocyte growth factor-regulated tyrosine kinase substrate) in endocytic and exocytic machineries. STAM is a component of the ESCRT (Endosomal Sorting Complex Required for Transport)-0 machinery and together with Hrs, functions to bind and sequester cargoes for downstream sorting into intralumenal vesicles.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889   1 MRRVNHKDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASEVSNVL-NKGHPKVCEKLKALMVEWTDEFKNDPQLSLIS 79
Cdd:cd16999    43 MKRVNHKVPHVALQALTLLGACVSNCGKIFHLEVCSRDFATEVRAVIkNKAHPKVCEKLKALMVEWSEEFQKDPQFSLIS 122

                          90
                  ....*....|....*..
gi 1248026889  80 AMIKNLKEQGVTFPAIG 96
Cdd:cd16999   123 ATIKSLKEEGITFPPAG 139

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 1248026889 163 RKVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFVTAD 217
Cdd:cd11964     1 RKVRAIYDFEAAEDNELTFKAGDIITILDDSDPNWWKGETPQGTGLFPSNFVTAD 55

Domain present in VPS-27, Hrs and STAM; Unpublished observations. Domain of unknown function.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889    1 MRRVNHKDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASEVSNVLNK--GHPKVCEKLKALMVEWTDEFKNDPQLSLI 78
Cdd:smart00288  43 KKRLNNKNPHVALLALTLLDACVKNCGSKFHLEVASKEFLNELVKLIKPkyPLPLVKKRILELIQEWADAFKNDPDLSQI 122

                           90
                   ....*....|.
gi 1248026889   79 SAMIKNLKEQG 89
Cdd:smart00288 123 VDVYDLLKKKG 133

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 1248026889 166 RAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQG-VGLFPS 211
Cdd:pfam00018   1 VALYDYTAQEPDELSFKKGDIIIVLEKSEDGWWKGRNKGGkEGLIPS 47

VHS (Vps27/Hrs/STAM) domain of Signal Transducing Adapter Molecule 2; Signal Transducing Adapter Molecule 2 (STAM2) is also called EAST (EGFR-Associated protein with SH3 and TAM domain) and Hbp (Hrs-binding protein). It is highly expressed in neurons, where it is localized in the nucleus. STAM (Signal Transducing Adaptor Molecule) subfamily members have at their N-termini a VHS domain, which is involved in cytokine-mediated intracellular signal transduction and has a superhelical structure similar to the structure of ARM (Armadillo) repeats, followed by a Ubiquitin-Interacting Motif (UIM) and a SH3 (Src Homology 3) domain, which is a well-established protein-protein interaction domain, and a GAT (GGA and TOM) domain. At the C-termini of most vertebrate STAMS, an Immunoreceptor Tyrosine-based Activation Motif (ITAM) is present, which mediates the binding of HRS (hepatocyte growth factor-regulated tyrosine kinase substrate) in endocytic and exocytic machineries. STAM is a component of the ESCRT (Endosomal Sorting Complex Required for Transport)-0 machinery and together with Hrs, functions to bind and sequester cargoes for downstream sorting into intralumenal vesicles.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889   1 MRRVNHKDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASEVSNVL-NKGHPKVCEKLKALMVEWTDEFKNDPQLSLIS 79
Cdd:cd16999    43 MKRVNHKVPHVALQALTLLGACVSNCGKIFHLEVCSRDFATEVRAVIkNKAHPKVCEKLKALMVEWSEEFQKDPQFSLIS 122

                          90
                  ....*....|....*..
gi 1248026889  80 AMIKNLKEQGVTFPAIG 96
Cdd:cd16999   123 ATIKSLKEEGITFPPAG 139

non-canonical GAT domain found in signal transducing adapter molecule 1 (STAM-1) and similar proteins; STAM-1 is involved in intracellular signal transduction mediated by cytokines and growth factors. It may also play a role in T-cell development. STAM-1 is a component of the ESCRT-0 complex that binds ubiquitin and acts as sorting machinery that recognizes ubiquitinated receptors and transfers them for further sequential lysosomal sorting/trafficking processes. Members of this subfamily contain a non-canonical GAT (GGA and Tom1) domain consisting of two helices. A canonical GAT domain is a monomeric three-helix bundle that bind to ubiquitin. STAM-1, together with another GAT domain-containing protein Hrs, forms a Hrs/STAM1 core complex that consists of two intertwined GAT domains, each consisting of two helices from one subunit, and one from the other subunit. The two GAT domains are connected by a two-stranded coiled-coil. The Hrs/STAM1 complex, an intertwined GAT heterodimer, is a scaffold for binding of ubiquitinated cargo proteins and coordinating ubiquitination and deubiquitination reactions that regulate sorting.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1248026889 251 FIDEDKMDQLLQMLQSTDPSDNQPDLPELLHLEAMCHQMGPLIDEKLEDIDRKHSELSELNVKVMEALSLYTKLMNE 327
Cdd:cd21389     1 YIDEDKMDQLLQMLQSADPTDDQPDLPELLHLEAMCHQMGPLIDEKLEDIDRKHSELSELNVKVMEALSLYAKLMNE 77

non-canonical GAT domain found in signal transducing adapter molecule 2 (STAM-2) and similar proteins; STAM-2 is a Hrs-binding protein involved in intracellular signal transduction mediated by cytokines and growth factors. STAM-2 is a component of the ESCRT-0 complex that binds ubiquitin and acts as sorting machinery that recognizes ubiquitinated receptors and transfers them for further sequential lysosomal sorting/trafficking processes. Members of this family contain a non-canonical GAT (GGA and Tom1) domain consisting of two helices. A canonical GAT domain is a monomeric three-helix bundle that bind to ubiquitin. STAM-2, together with another GAT domain-containing protein Hrs, forms a Hrs/STAM2 core complex that consists of two intertwined GAT domains, each consisting of two helices from one subunit, and one from the other subunit. The two GAT domains are connected by a two-stranded coiled-coil. The Hrs/STAM2 complex, an intertwined GAT heterodimer, is a scaffold for binding of ubiquitinated cargo proteins and coordinating ubiquitination and deubiquitination reactions that regulate sorting.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889 246 EPEPAFIDEDKMDQLLQMLQSTDPSDNQPDLPELLHLEAMCHQMGPLIDEKLEDIDRKHSELSELNVKVMEALSLYTKLM 325
Cdd:cd21390     1 EPEPVYIDEEKMDKTLQLLQSIDPTDSKPDSPELLDLEDICQQMGPMIDEKLEEIDRKHSELSELNVKVLEALELYNKLM 80

                          90
                  ....*....|.
gi 1248026889 326 NEDPMYSMYAK 336
Cdd:cd21390    81 NEAPMYSVYSK 91

non-canonical GAT domain found in metazoan signal transducing adapter molecules (STAMs) and similar proteins; STAMs are Hrs-binding proteins involved in intracellular signal transduction mediated by cytokines and growth factors. They are components of the ESCRT-0 complex that binds ubiquitin and acts as sorting machinery that recognizes ubiquitinated receptors and transfers them for further sequential lysosomal sorting/trafficking processes. Members of this family contain a non-canonical GAT (GGA and Tom1) domain consisting of two helices. A canonical GAT domain is a monomeric three-helix bundle that bind to ubiquitin. STAM, together with another GAT domain-containing protein Hrs, forms a Hrs/STAM core complex that consists of two intertwined GAT domains, each consisting of two helices from one subunit, and one from the other subunit. The two GAT domains are connected by a two-stranded coiled-coil. The Hrs/STAM complex, an intertwined GAT heterodimer, is a scaffold for binding of ubiquitinated cargo proteins and coordinating ubiquitination and deubiquitination reactions that regulate sorting.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1248026889 251 FIDEDKMDQLLQMLQSTDPSDNQPDLPELLHLEAMCHQMGPLIDEKLEDIDRKHSELSELNVKVMEALSLYTKLMNE 327
Cdd:cd21388     1 EIDEEKIDRCLQMLQNADPTGERPDPPELLQLEAECKQMGPLIDAELERIDRKHAELTELNVKLMDALALYHDLMQE 77

Src homology 3 domain of Signal Transducing Adaptor Molecule 2; STAM2, also called EAST (Epidermal growth factor receptor-associated protein with SH3 and TAM domain) or Hbp (Hrs binding protein), is part of the endosomal sorting complex required for transport (ESCRT-0). It plays a role in sorting mono-ubiquinated endosomal cargo for trafficking to the lysosome for degradation. It is also involved in the regulation of exocytosis. STAMs were discovered as proteins that are highly phosphorylated following cytokine and growth factor stimulation. They function in cytokine signaling and surface receptor degradation, as well as regulate Golgi morphology. They associate with many proteins including Jak2 and Jak3 tyrosine kinases, Hrs, AMSH, and UBPY. STAM adaptor proteins contain VHS (Vps27, Hrs, STAM homology), ubiquitin interacting (UIM), and SH3 domains. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*.
gi 1248026889 163 RKVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFVTADL 218
Cdd:cd11963     2 RKVRALYDFEAVEDNELTFKHGEIIIVLDDSDANWWKGENHRGVGLFPSNFVTTDL 57

Domain present in VPS-27, Hrs and STAM; Unpublished observations. Domain of unknown function.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889    1 MRRVNHKDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASEVSNVLNK--GHPKVCEKLKALMVEWTDEFKNDPQLSLI 78
Cdd:smart00288  43 KKRLNNKNPHVALLALTLLDACVKNCGSKFHLEVASKEFLNELVKLIKPkyPLPLVKKRILELIQEWADAFKNDPDLSQI 122

                           90
                   ....*....|.
gi 1248026889   79 SAMIKNLKEQG 89
Cdd:smart00288 123 VDVYDLLKKKG 133

VHS (Vps27/Hrs/STAM) domain family; The VHS domain is present in Vps27 (Vacuolar Protein Sorting), Hrs (Hepatocyte growth factor-regulated tyrosine kinase substrate) and STAM (Signal Transducing Adaptor Molecule). It has a superhelical structure similar to that of the ARM (Armadillo) repeats and is present at the N-termini of proteins involved in intracellular membrane trafficking. There are four general groups of VHS domain containing proteins based on their association with other domains. The first group consists of proteins of the STAM/EAST/Hbp family, which has the domain composition of VHS-SH3-ITAM. The second consists of proteins with a FYVE domain C-terminal to VHS. The third consists of GGA proteins with a domain composition of VHS-GAT (GGA and TOM)-GAE (Gamma-Adaptin Ear) domain. The fourth consists of proteins with a VHS domain alone or with domains other than those mentioned above. In GGA proteins, VHS domains are involved in cargo recognition in trans-Golgi, thereby having a general membrane targeting/cargo recognition role in vesicular trafficking.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889   2 RRVNHKDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASEVSNVLNK--GHPKVCEKLKALMVEWTDEFKNDPQLSLIS 79
Cdd:cd03561    44 KRLQSKNPKVQLLALTLLETLVKNCGAPFHSEVASRDFLQELVKLVKKkkTSPEVREKALALIQEWAEAFQGDGRLPLFY 123

                  ....*..
gi 1248026889  80 AMIKNLK 86
Cdd:cd03561   124 DTYQQLR 130

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

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd11805     1 RVQALYDFNPQEPGELEFRRGDIITVLDSSDPDWWKGELRGRVGIFPANYVQ 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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQG-VGLFPSNF 213
Cdd:cd00174     1 YARALYDYEAQDDDELSFKKGDIITVLEKDDDGWWEGELNGGrEGLFPANY 51

C-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 has 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 C-terminal SH3 domain of GRAP2 binds to different motifs found in substrate peptides including the typical PxxP motif in hematopoietic progenitor kinase 1 (HPK1), the RxxK motif in SLP-76 and HPK1, and the RxxxxK motif in phosphatase-like protein HD-PTP. SH3 domains are protein interaction domains that typically bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 1248026889 165 VRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:cd11950     2 VRALYDFEALEDDELGFNSGDVIEVLDSSNPSWWKGRLHGKLGLFPANYV 51

Fifth Src homology 3 domain (or SH3E) 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 fifth SH3 domain (or SH3E) of ITSN1 has been shown to bind many protein partners including SGIP1, Sos1, dynamin1/2, CIN85, c-Cbl, SHIP2, N-WASP, and synaptojanin-1, 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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd11840     1 QVIALFPYTAQNEDELSFQKGDIINVLSKDDPDWWRGELNGQTGLFPSNYVE 52

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 1248026889 166 RAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQG-VGLFPS 211
Cdd:pfam00018   1 VALYDYTAQEPDELSFKKGDIIIVLEKSEDGWWKGRNKGGkEGLIPS 47

VHS (Vps27/Hrs/STAM) domain of Hepatocyte growth factor-regulated tyrosine kinase substrate, Hrs; Hrs (Hepatocyte growth factor-regulated tyrosine kinase substrate) plays a role in at least three vesicle trafficking events: exocytosis, endocytosis, and endosome to lysosome trafficking. Hrs is involved in promoting rapid recycling of endocytosed signaling receptors to the plasma membrane. Together with STAM or STAM2, it comprises the ESCRT (Endosomal Sorting Complex Required for Transport)-0 machinery, which functions to bind and sequester cargoes for downstream sorting into intralumenal vesicles. Hrs contains an N-terminal VHS domain, which has a superhelical structure similar to the structure of ARM (Armadillo) repeats, a FYVE (Fab1p, YOTB, Vac1p, and EEA1) zinc finger domain, a Double Ubiquitin-Interacting Motif (DUIM), a P(S/T)XP motif that recruit ESCRT-I, a GAT (GGA and TOM) domain, and a short peptide motif near the C-terminus that recruits clathrin.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889   2 RRVNHKDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASEVSNVLNK-GHPKVCEKLKALMVEWTDEFKNDPQLSLISA 80
Cdd:cd03569    46 KKLNDQNPHVALYALQVLESVVKNCGTPVHDEVATKEFMEELRDLVKTtTSENVRNKILELIQAWAHAFRNEPKYKIVQD 125

                          90
                  ....*....|...
gi 1248026889  81 MIKNLKEQGVTFP 93
Cdd:cd03569   126 TYNIMKMEGYKFP 138

Third Src Homology 3 domain (SH3C) of CD2-associated protein and similar proteins; This subfamily is composed of the third SH3 domain (SH3C) 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. SH3C of both proteins have been shown to bind to 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        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVL--DDSDPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd11875     1 KARVLFDYEAENEDELTLREGDIVTILskDCEDKGWWKGELNGKRGVFPDNFVE 54

Fifth Src homology 3 domain (or SH3E) 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 fifth SH3 domain (or SH3E) of ITSN1 has been shown to bind many protein partners including SGIP1, Sos1, dynamin1/2, CIN85, c-Cbl, SHIP2, N-WASP, and synaptojanin-1, 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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:cd11995     2 QVIGMYDYTAQNDDELAFSKGQIINVLNKEDPDWWKGELNGQVGLFPSNYV 52

VHS (Vps27/Hrs/STAM) domain of Tom1 subfamily; This subfamily is composed of Tom1 (Target of myb1 - retroviral oncogene) protein, Tom1L1 (Tom1-like1), Tom1L2 (Tom1-like2), and similar proteins. Proteins belonging to this subfamily are characterized by the presence of a VHS (Vps27p/Hrs/Stam) domain in the N-terminal portion followed by a GAT (GGA and Tom) domain. They are novel regulators for post-Golgi trafficking and signaling. Yeast do not contain homologous proteins of the Tom1 subfamily, suggesting these proteins have evolved to accommodate more complex cellular processes. Tom1 is essential for the negative regulation of Interleukin-1 and Tumor Necrosis Factor-induced signaling pathways. The VHS domain has a superhelical structure similar to the structure of the ARM repeats and is present at the very N-termini of proteins. It is a right-handed superhelix of eight alpha helices. The VHS domain has been found in a number of proteins, some of which have been implicated in intracellular trafficking and sorting.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889   7 KDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASEVSNVLN-KGHPKVC--EKLKALMVEWTDEFKNDPQLSLISAMIK 83
Cdd:cd03565    53 KNHTVVMYTLTLLETCVKNCGHRFHVLVANKDFLQELVKLIGpKNDPPTIvqEKVLSLIQSWADAFRGQPDLQEVVKVYQ 132

                  ....*.
gi 1248026889  84 NLKEQG 89
Cdd:cd03565   133 ELKAKG 138

VHS (Vps27/Hrs/STAM) domain of Class E vacuolar protein-sorting machinery protein HSE1; Class E vacuolar protein-sorting machinery protein HSE1, together with Vps27, comprise the ESCRT-0 complex, the sorting receptor for ubiquitinated cargo proteins at the multivesicular body (MVB). The complex directly binds to ubiquitinated transmembrane proteins and recruits both ubiquitin ligases and deubiquitinating enzymes. It is also required the efficient recycling of late Golgi proteins including the carboxypeptidase Y (CPY) sorting receptor, Vps10. Similar to metazoan STAMs, HSE1 contain: an N-terminal VHS domain, which is involved in cytokine-mediated intracellular signal transduction and has a superhelical structure similar to the structure of ARM (Armadillo) repeats; a Ubiquitin-Interacting Motif (UIM); a SH3 (Src Homology 3) domain, a well-established protein-protein interaction domain; and a GAT (GGA and TOM) domain, which is essential for the normal sorting function of HSE1.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889   2 RRVNHKDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASEVSNVLN--KGHPKVCEKLKALMVEWTDEFKNDPQLSLIS 79
Cdd:cd16978    45 KRLQHRNANVQLRSLSLADALAKNCGSRLHQEISSRSFTQTLLRLINdrTTHATVKKRILELIKQLSDSFKSDPSLGLMS 124

                          90
                  ....*....|
gi 1248026889  80 AMIKNLKEQG 89
Cdd:cd16978   125 DTYDQLKSKY 134

Src homology 3 domain of eumetazoan Actin-binding protein 1; Abp1, also called drebrin-like protein, is an adaptor protein that functions in receptor-mediated endocytosis and vesicle trafficking. It contains an N-terminal actin-binding module, the actin-depolymerizing factor (ADF) homology domain, a helical domain, and a C-terminal SH3 domain. Mammalian Abp1, unlike yeast Abp1, does not contain an acidic domain that interacts with the Arp2/3 complex. It regulates actin dynamics indirectly by interacting with dynamin and WASP family proteins. Abp1 deficiency causes abnormal organ structure and function of the spleen, heart, and lung of mice. 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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQG-VGLFPSNFVT 215
Cdd:cd11960     1 RARALYDYQAADDTEISFDPGDIITDIEQIDEGWWRGTGPDGtYGLFPANYVE 53

Src homology 3 domain of ARHGEF9-like Rho guanine nucleotide exchange factors; Members of this family contain a SH3 domain followed by RhoGEF (also called Dbl-homologous or DH) and Pleckstrin Homology (PH) domains. They include the Rho guanine nucleotide exchange factors ARHGEF9, ASEF (also called ARHGEF4), ASEF2, and similar proteins. GEFs activate small GTPases by exchanging bound GDP for free GTP. ARHGEF9 specifically activates Cdc42, while both ASEF and ASEF2 can activate Rac1 and Cdc42. ARHGEF9 is highly expressed in the brain and it interacts with gephyrin, a postsynaptic protein associated with GABA and glycine receptors. ASEF plays a role in angiogenesis and cell migration. ASEF2 is important in cell migration and adhesion dynamics. ASEF exists in an autoinhibited form and is activated upon binding of the tumor suppressor APC (adenomatous polyposis coli), leading to the activation of Rac1 or Cdc42. In its autoinhibited form, the SH3 domain of ASEF forms an extensive interface with the DH and PH domains, blocking the Rac binding site. 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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:cd11828     1 LAEALWDHVTMDPEELGFKAGDVIEVLDMSDKDWWWGSIRDEEGWFPASFV 51

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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:pfam07653   1 YGRVIFDYVGTDKNGLTLKKGDVVKVLGKDNDGWWEGETGGRVGLVPSTAV 51

First Src Homology 3 domain of Sorbin and SH3 domain containing (Sorbs) proteins and similar domains; This family, also called the vinexin family, is composed predominantly of adaptor proteins containing one sorbin homology (SoHo) and three SH3 domains. Members include the first SH3 domains of Sorbs1 (or ponsin), Sorbs2 (or ArgBP2), Vinexin (or Sorbs3), and similar domains. They are involved in the regulation of cytoskeletal organization, cell adhesion, and growth factor signaling. Members of this family bind multiple partners including signaling molecules like c-Abl, c-Arg, Sos, and c-Cbl, as well as cytoskeletal molecules such as vinculin and afadin. They may have overlapping functions. 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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:cd11781     1 KARALYPFKAQSAKELSLKKGDIIYIRRQIDKNWYEGEHNGRVGIFPASYV 51

VHS (Vps27/Hrs/STAM) domain of Target of Myb protein 1; Tom1 (Target of myb1 - retroviral oncogene) is a novel negative regulator of interleukin-1 and tumor necrosis factor-induced signaling pathways. It also plays important roles in protein-degradation systems in Alzheimer's disease pathogenesis. Tom1 contains VHS and GAT domains in the N-terminal and central region, respectively. The VHS domain has a superhelical structure similar to the structure of the ARM repeats and is present at the very N-termini of proteins. It is a right-handed superhelix of eight alpha helices. The VHS domain has been found in a number of proteins, some of which have been implicated in intracellular trafficking and sorting. The VHS domain of Tom1 is essential for its function as a negative regulator.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1248026889   2 RRVNHKDPHVAMQALTLLGACVSNCGKIFHLEVCSRDFASE--VSNVLNKGHPK--VCEKLKALMVEWTDEFKNDPQLSL 77
Cdd:cd16995    46 RIVGNKNFREVMLALTVLETCVKNCGHRFHVLVASQDFVEGvlVKTILPKNNPPaiVHDKVLNLIQAWADAFRSSPDLTG 125

                          90
                  ....*....|..
gi 1248026889  78 ISAMIKNLKEQG 89
Cdd:cd16995   126 VVTVYEDLRRKG 137

Src homology 3 domain of Cortactin; Cortactin was originally identified as a substrate of Src kinase. It is an actin regulatory protein that binds to the Arp2/3 complex and stabilizes branched actin filaments. It is involved in cellular processes that affect cell motility, adhesion, migration, endocytosis, and invasion. It is expressed ubiquitously except in hematopoietic cells, where the homolog hematopoietic lineage cell-specific 1 (HS1) is expressed instead. Cortactin contains an N-terminal acidic domain, several copies of a repeat domain found in cortactin and HS1, a proline-rich region, and a C-terminal SH3 domain. The N-terminal region interacts with the Arp2/3 complex and F-actin, and is crucial in regulating branched actin assembly. Cortactin also serves as a scaffold and provides a bridge to the actin cytoskeleton for membrane trafficking and signaling proteins that bind to its SH3 domain. Binding partners for the SH3 domain of cortactin include dynamin2, N-WASp, MIM, FGD1, among others. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 1248026889 167 AVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:cd11959     4 ALYDYQAADDDEISFDPDDIITNIEMIDEGWWRGVCRGKYGLFPANYV 51

Src homology 3 domain of SH3 domain containing Ysc84-like 1 (SH3YL1) protein; SH3YL1 localizes to the plasma membrane and is required for dorsal ruffle formation. It binds phosphoinositides (PIs) with high affinity through its N-terminal SYLF domain (also called DUF500). In addition, SH3YL1 contains a C-terminal SH3 domain which has been reported to bind to N-WASP, dynamin 2, and SHIP2 (a PI 5-phosphatase). 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 1248026889 165 VRAVYDFEAAEDNELTFKAGEIITVLD--DSDPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd11841     2 VTALYSFEGQQPCDLSFQAGDRITVLTrtDSQFDWWEGRLRGRVGIFPANYVS 54

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        50
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd11874     1 RCKVLFSYTPQNEDELELKVGDTIEVLGEVEEGWWEGKLNGKVGVFPSNFVK 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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQG-VGLFPSNFVT 215
Cdd:cd11768     1 IVVALYDFQPIEPGDLPLEKGEEYVVLDDSNEHWWRARDKNGnEGYIPSNYVT 53

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

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 1248026889 167 AVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:cd11986     4 ALYRFKALEKDDLDFHPGERITVIDDSNEEWWRGKIGEKTGYFPMNFI 51

Fifth 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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNF 213
Cdd:cd11818     1 KARALYDFTGENEDELSFKAGDIITELESIDEEWMSGELRGKSGIFPKNF 50

Src homology 3 domain of Protein kinase C and Casein kinase Substrate in Neurons 1 (PACSIN1) and PACSIN 2; PACSIN 1 or Syndapin I (Synaptic dynamin-associated protein I) is expressed specifically in the brain and is localized in neurites and synaptic boutons. It binds the brain-specific proteins dynamin I, synaptojanin, synapsin I, and neural Wiskott-Aldrich syndrome protein (nWASP), and functions as a link between the cytoskeletal machinery and synaptic vesicle endocytosis. PACSIN 1 interacts with huntingtin and may be implicated in the neuropathology of Huntington's disease. PACSIN 2 or Syndapin II is expressed ubiquitously and is involved in the regulation of tubulin polymerization. It associates with Golgi membranes and forms a complex with dynamin II which is crucial in promoting vesicle formation from the trans-Golgi network. PACSINs act as regulators of cytoskeletal and membrane dynamics. Vetebrates harbor three isoforms with distinct expression patterns and specific functions. PACSINs contain 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 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPN-WWKGETHQG-VGLFPSNFVTA 216
Cdd:cd11998     2 RVRALYDYDGQEQDELSFKAGDELTKLEDEDEQgWCKGRLDSGqVGLYPANYVEP 56

Second Src Homology 3 domain of FCH and double SH3 domains proteins; This group is composed of FCH and double SH3 domains protein 1 (FCHSD1) and FCHSD2. These proteins have a common domain structure consisting of an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs), two SH3, and C-terminal proline-rich domains. They have only been characterized in silico and their functions remain unknown. This group also includes the insect protein, nervous wreck, which acts as a regulator of synaptic growth signaling. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1248026889 165 VRAVYDFEAAEDNELTFKAGEIITVL----DDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:cd11762     2 VRALYDYEAQSDEELSFPEGAIIRILrkddNGVDDGWWEGEFNGRVGVFPSLVV 55

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        50
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd11766     1 PAVVKFNYEAQREDELSLRKGDRVLVLEKSSDGWWRGECNGQVGWFPSNYVT 52

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

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd12046     1 QVVALFSYEASQPEDLEFQKGDVILVLSKVNEDWLEGQCKGKIGIFPSAFVE 52

Third Src Homology 3 domain (SH3C) of CD2-associated protein; CD2AP, also called CMS (Cas ligand with Multiple SH3 domains) or METS1 (Mesenchyme-to-Epithelium Transition protein with SH3 domains), is a cytosolic adaptor protein that plays a role in regulating the cytoskeleton. It is critical in cell-to-cell union necessary for kidney function. It also stabilizes the contact between a T cell and antigen-presenting cells. It is primarily expressed in podocytes at the cytoplasmic face of the slit diaphragm and serves as a linker anchoring podocin and nephrin to the actin cytoskeleton. CD2AP contains three SH3 domains, a proline-rich region, and a C-terminal coiled-coil domain. All of these domains enable CD2AP to bind various protein partners and assemble complexes that have been implicated in many different functions. This alignment model represents the third SH3 domain (SH3C) of CD2AP. SH3C has been shown to bind 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        50
                  ....*....|....*....|....*....|....*....|....*....|.
gi 1248026889 166 RAVYDFEAAEDNELTFKAGEIITVL--DDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:cd12056     5 KALFHYEGTNEDELDFKEGEIILIIskDTGEPGWWKGELNGKEGVFPDNFV 55

Src Homology 3 domain of Mixed Lineage Kinases 1, 2, and 3; MLKs 1, 2, and 3 are Serine/Threonine Kinases (STKs), catalyzing the transfer of the gamma-phosphoryl group from ATP to S/T residues on protein substrates. MLKs act as mitogen-activated protein kinase kinase kinases (MAP3Ks, MKKKs, MAPKKKs), which phosphorylate and activate MAPK kinases (MAPKKs or MKKs or MAP2Ks), which in turn phosphorylate and activate MAPKs during signaling cascades that are important in mediating cellular responses to extracellular signals. MLKs play roles in immunity and inflammation, as well as in cell death, proliferation, and cell cycle regulation. Little is known about the specific function of MLK1, also called MAP3K9. It is capable of activating the c-Jun N-terminal kinase pathway. Mice lacking both MLK1 and MLK2 are viable, fertile, and have normal life spans. MLK2, also called MAP3K10, is abundant in brain, skeletal muscle, and testis. It functions upstream of the MAPK, c-Jun N-terminal kinase. It binds hippocalcin, a calcium-sensor protein that protects neurons against calcium-induced cell death. Both MLK2 and hippocalcin may be associated with the pathogenesis of Parkinson's disease. MLK3, also called MAP3K11, is highly expressed in breast cancer cells and its signaling through c-Jun N-terminal kinase has been implicated in the migration, invasion, and malignancy of cancer cells. It also functions as a negative regulator of Inhibitor of Nuclear Factor-KappaB Kinase (IKK) and thus, impacts inflammation and immunity. MLKs contain an SH3 domain, a catalytic kinase domain, a leucine zipper, a proline-rich region, and a CRIB domain that mediates binding to GTP-bound Cdc42 and Rac. 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 1248026889 167 AVYDFEAAEDNELTFKAGEIITVLD-DS----DPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd12059     4 AVFDYEASAEDELTLRRGDRVEVLSkDSavsgDEGWWTGKINDRVGIFPSNYVT 57

Src Homology 3 domain of Mixed Lineage Kinases; MLKs are Serine/Threonine Kinases (STKs), catalyzing the transfer of the gamma-phosphoryl group from ATP to S/T residues on protein substrates. MLKs act as mitogen-activated protein kinase kinase kinases (MAP3Ks, MKKKs, MAPKKKs), which phosphorylate and activate MAPK kinases (MAPKKs or MKKs or MAP2Ks), which in turn phosphorylate and activate MAPKs during signaling cascades that are important in mediating cellular responses to extracellular signals. MLKs play roles in immunity and inflammation, as well as in cell death, proliferation, and cell cycle regulation. Mammals have four MLKs (MLK1-4), mostly conserved in vertebrates, which contain an SH3 domain, a catalytic kinase domain, a leucine zipper, a proline-rich region, and a CRIB domain that mediates binding to GTP-bound Cdc42 and Rac. 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 1248026889 167 AVYDFEAAEDNELTFKAGEIITVLD-----DSDPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd11876     4 ALFDYDARGEDELTLRRGQPVEVLSkdaavSGDEGWWTGKIGDKVGIFPSNYVA 57

First Src Homology 3 domain (SH3A) of Cbl-interacting protein of 85 kDa; CIN85, also called SH3 domain-containing kinase-binding protein 1 (SH3KBP1) or CD2-binding protein 3 (CD2BP3) or Ruk, is an adaptor protein that is involved in the downregulation of receptor tyrosine kinases by facilitating endocytosis through interaction with endophilin-associated ubiquitin ligase Cbl proteins. It is also important in many other cellular processes including vesicle-mediated transport, cytoskeletal remodelling, apoptosis, cell adhesion and migration, and viral infection, among others. CIN85 exists as multiple variants from alternative splicing; the main variant contains three SH3 domains, a proline-rich region, and a C-terminal coiled-coil domain. All of these domains enable CIN85 to bind various protein partners and assemble complexes that have been implicated in many different functions. This alignment model represents the first SH3 domain (SH3A) of CIN85; SH3A binds to internal proline-rich motifs within the proline-rich region. This intramolecular interaction serves as a regulatory mechanism to keep CIN85 in a closed conformation, preventing the recruitment of other proteins. SH3A has also been shown to bind ubiquitin and to an atypical PXXXPR motif at the C-terminus of Cbl and the cytoplasmic end of the cell adhesion protein CD2. 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 1248026889 169 YDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFV 214
Cdd:cd12052     6 FDYKAQHEDELTITVGDIITKIKKDDGGWWEGEIKGRRGLFPDNFV 51

First Src Homology 3 domain (SH3A) of CD2-associated protein and similar proteins; This subfamily is composed of the first SH3 domain (SH3A) 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. SH3A of both proteins bind to an atypical PXXXPR motif at the C-terminus of Cbl and the cytoplasmic domain of the cell adhesion protein CD2. CIN85 SH3A binds to internal proline-rich motifs within the proline-rich region; this intramolecular interaction serves as a regulatory mechanism to keep CIN85 in a closed conformation, preventing the recruitment of other proteins. CIN85 SH3A has also been shown to bind 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        50
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1248026889 164 KVRAVYDFEAAEDNELTFKAGEIITVLDDSDPNWWKGETHQGVGLFPSNFVT 215
Cdd:cd11873     1 EVIVEFDYDAEEPDELTLKVGDIITNVKKMEEGWWEGTLNGKRGMFPDNFVK 52