Protein kinase C-related kinase homology region 1 (HR1) Rho-binding domain of vertebrate Cdc42-Interacting Protein 4 and FormiN Binding Protein 1-Like; CIP4 and FNBP1L are Cdc42 effectors that bind Wiskott-Aldrich syndrome protein (WASP) and function in endocytosis. FNBP1L, also called Toca-1 (Transducer of Cdc42-dependent actin assembly 1), forms a complex with neural WASP; the complex induces the formation of filopodia and endocytic vesicles. FNBP1L is required for Cdc42-induced actin assembly and is essential for autophagy of intracellular pathogens. CIP4 may also play a role in phagocytosis. It functions downstream of Cdc42 in PDGF-dependent actin reorganization and cell migration, and also regulates the activity of PDGFRbeta. It uses Src as a substrate in regulating the invasiveness of breast tumor cells. CIP4 may also play a role in the pathogenesis of Huntington's disease. CIP4 and FNBP1L contain an N-terminal F-BAR domain, a central HR1 domain, and a C-terminal SH3 domain. HR1 domains are anti-parallel coiled-coil (ACC) domains that bind small GTPases from the Rho family; the HR1 domain of CIP4 binds Cdc42 and TC10. Translocation of CIP4 is facilitated by its binding to TC10 at the plasma membrane.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119 399 PPEQRRKKLQQRIDELNRELQKESDQKDALNKMKDVYEKNPQMGDPGSLQPKLAETMNNIDRLRMEIHKNEAWLSEVEGK 478
Cdd:cd11628    1 PPEQRRKRLQQKIDELSRELQKEMDQSEALMKMKDVYEKNPQMGDPASLQPQIAETASNIDRLRGELHKYEAWLAEAEGR 80

                 .
gi 663434119 479 T 479
Cdd:cd11628   81 V 81

Protein kinase C-related kinase homology region 1 (HR1) Rho-binding domain of vertebrate Cdc42-Interacting Protein 4 and FormiN Binding Protein 1-Like; CIP4 and FNBP1L are Cdc42 effectors that bind Wiskott-Aldrich syndrome protein (WASP) and function in endocytosis. FNBP1L, also called Toca-1 (Transducer of Cdc42-dependent actin assembly 1), forms a complex with neural WASP; the complex induces the formation of filopodia and endocytic vesicles. FNBP1L is required for Cdc42-induced actin assembly and is essential for autophagy of intracellular pathogens. CIP4 may also play a role in phagocytosis. It functions downstream of Cdc42 in PDGF-dependent actin reorganization and cell migration, and also regulates the activity of PDGFRbeta. It uses Src as a substrate in regulating the invasiveness of breast tumor cells. CIP4 may also play a role in the pathogenesis of Huntington's disease. CIP4 and FNBP1L contain an N-terminal F-BAR domain, a central HR1 domain, and a C-terminal SH3 domain. HR1 domains are anti-parallel coiled-coil (ACC) domains that bind small GTPases from the Rho family; the HR1 domain of CIP4 binds Cdc42 and TC10. Translocation of CIP4 is facilitated by its binding to TC10 at the plasma membrane.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119 399 PPEQRRKKLQQRIDELNRELQKESDQKDALNKMKDVYEKNPQMGDPGSLQPKLAETMNNIDRLRMEIHKNEAWLSEVEGK 478
Cdd:cd11628    1 PPEQRRKRLQQKIDELSRELQKEMDQSEALMKMKDVYEKNPQMGDPASLQPQIAETASNIDRLRGELHKYEAWLAEAEGR 80

                 .
gi 663434119 479 T 479
Cdd:cd11628   81 V 81

Fes/CIP4, and EFC/F-BAR homology domain; Alignment extended from. Highly alpha-helical. The cytosolic endocytic adaptor proteins in fungi carry this domain at the N-terminus; several of these have been referred to as muniscin proteins. These N-terminal BAR, N-BAR, and EFC/F-BAR domains are found in proteins that regulate membrane trafficking events by inducing membrane tubulation. The domain dimerizes into a curved structure that binds to liposomes and either senses or induces the curvature of the membrane bilayer to cause biophysical changes to the shape of the bilayer; it also thereby recruits other trafficking factors, such as the GTPase dynamin. Most EFC/F-BAR domain-family members localize to actin-rich structures.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 663434119   10 QFDSLDKHTQWGIDFLERYAKFVKERIEIEQNYAKQLRNLVKKYCpKRSSKDEEPRFTSCVAFFNILNELNDYAGQRE 87
Cdd:pfam00611   1 GFKVLLKRLKQGIKLLEELASFLKERAEIEEEYAKKLQKLAKKFL-KKKKKPEDDGGTLKKAWDELLTETEQLAKQHL 77

Fes/CIP4 homology domain; Alignment extended from original report. Highly alpha-helical. Also known as the RAEYL motif or the S. pombe Cdc15 N-terminal domain.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119     1 MSWGTELWDQFDSLDKHTQWGIDFLERYAKFVKERIEIEQNYAKQLRNLVKKYcpkRSSKDEEPRFTS-CVAFFNILNEL 79
Cdd:smart00055   1 MGFWSELDDGFEALLSRLKNGLRLLEDLKKFMRERAKIEEEYAKKLQKLSKKL---RAVRDTEPEYGSlSKAWEVLLSET 77

                   ....*...
gi 663434119    80 NDYAGQRE 87
Cdd:smart00055  78 DALAKQHL 85

Uncharacterized conserved protein YgiM, contains N-terminal SH3 domain, DUF1202 family [General function prediction only];

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|...
gi 663434119 555 GTLamKEGEVLYIIEEDkgDGWTRARRQNGEEGYVPTSYIDVT 597
Cdd:COG3103   28 GTL--PKGEKVTVLGRS--GGWYKVRYSNGKTGWVSSRYLTVT 66

The F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs) domain of Cdc42-Interacting Protein 4 and similar proteins; F-BAR domains are dimerization modules that bind and bend membranes and are found in proteins involved in membrane dynamics and actin reorganization. This subfamily is composed of Cdc42-Interacting Protein 4 (CIP4), Formin Binding Protein 17 (FBP17), FormiN Binding Protein 1-Like (FNBP1L), and similar proteins. CIP4 and FNBP1L are Cdc42 effectors that bind Wiskott-Aldrich syndrome protein (WASP) and function in endocytosis. CIP4 and FBP17 bind to the Fas ligand and may be implicated in the inflammatory response. CIP4 may also play a role in phagocytosis. Members of this subfamily typically contain an N-terminal F-BAR domain and a C-terminal SH3 domain. In addition, some members such as FNBP1L contain a central Cdc42-binding HR1 domain. F-BAR domains form banana-shaped dimers with a positively-charged concave surface that binds to negatively-charged lipid membranes. They can induce membrane deformation in the form of long tubules.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119   5 TELWDQFDSLDKHTQWGIDFLERYAKFVKERIEIEQNYAKQLRNLVKKYCPKRSSKDEEpRFTSCVAFFNILNELNDYAG 84
Cdd:cd07653    1 TELWDQFDNLEKHTQKGIDFLERYGKFVKERAAIEQEYAKKLRKLVKKYLPKKKEEDEY-SFSSVKAFRSILNEVNDIAG 79

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119  85 QREVVAEEMAHRVYGELMRYAHDLKTERKMHLQEGRKAQQYLDMCWKQMDNSKKKFERECREAEKAQQSYERLDNDTNAT 164
Cdd:cd07653   80 QHELIAENLNSNVCKELKTLISELRQERKKHLSEGSKLQQKLESSIKQLEKSKKAYEKAFKEAEKAKQKYEKADADMNLT 159

                        170       180       190       200       210       220       230       240
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119 165 KADVEKAKQQLNLRTHMADENKNEYAAQLQNFNGEQHKHFYVVIPQIYKQLQEMDERRTIKLSECYRGFADSERKVIPII 244
Cdd:cd07653  160 KADVEKAKANANLKTQAAEEAKNEYAAQLQKFNKEQRQHYSTDLPQIFDKLQELDEKRINRTVELLLQAAEIERKVIPII 239

                        250
                 ....*....|.
gi 663434119 245 SKCLEGMILAA 255
Cdd:cd07653  240 AKCLDGIKKAG 250

Protein kinase C-related kinase homology region 1 (HR1) Rho-binding domain of vertebrate Cdc42-Interacting Protein 4 and FormiN Binding Protein 1-Like; CIP4 and FNBP1L are Cdc42 effectors that bind Wiskott-Aldrich syndrome protein (WASP) and function in endocytosis. FNBP1L, also called Toca-1 (Transducer of Cdc42-dependent actin assembly 1), forms a complex with neural WASP; the complex induces the formation of filopodia and endocytic vesicles. FNBP1L is required for Cdc42-induced actin assembly and is essential for autophagy of intracellular pathogens. CIP4 may also play a role in phagocytosis. It functions downstream of Cdc42 in PDGF-dependent actin reorganization and cell migration, and also regulates the activity of PDGFRbeta. It uses Src as a substrate in regulating the invasiveness of breast tumor cells. CIP4 may also play a role in the pathogenesis of Huntington's disease. CIP4 and FNBP1L contain an N-terminal F-BAR domain, a central HR1 domain, and a C-terminal SH3 domain. HR1 domains are anti-parallel coiled-coil (ACC) domains that bind small GTPases from the Rho family; the HR1 domain of CIP4 binds Cdc42 and TC10. Translocation of CIP4 is facilitated by its binding to TC10 at the plasma membrane.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119 399 PPEQRRKKLQQRIDELNRELQKESDQKDALNKMKDVYEKNPQMGDPGSLQPKLAETMNNIDRLRMEIHKNEAWLSEVEGK 478
Cdd:cd11628    1 PPEQRRKRLQQKIDELSRELQKEMDQSEALMKMKDVYEKNPQMGDPASLQPQIAETASNIDRLRGELHKYEAWLAEAEGR 80

                 .
gi 663434119 479 T 479
Cdd:cd11628   81 V 81

Protein kinase C-related kinase homology region 1 (HR1) Rho-binding domain of Formin Binding Protein 17; FBP17, also called FormiN Binding Protein 1 (FNBP1), is involved in dynamin-mediated endocytosis. It is recruited to clathrin-coated pits late in the endocytosis process and may play a role in the invagination and scission steps. FBP17 binds in vivo to tankyrase, a protein involved in telomere maintenance and mitogen activated protein kinase (MAPK) signaling. It also binds to the Fas ligand and may be implicated in the inflammatory response. FBP17 contains an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs) domain, central HR1 domain, and a C-terminal SH3 domain. HR1 domains are anti-parallel coiled-coil (ACC) domains that bind small GTPases from the Rho family; the HR1 domain of the related protein, CIP4, binds Cdc42 and TC10. Translocation of CIP4 is facilitated by its binding to TC10 at the plasma membrane.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 663434119 400 PEQRRKKLQQRIDELNRELQKESDQKDALNKMKDVYEKNPQMGDPGSLQPKLAETMNNIDRLRMEIHKNEAWLSEVE 476
Cdd:cd11629    1 PEQRRKKLQQKVDELNKDIQKEMDQRDALTKMKDVYIKNPQMGDPASVDHRLEEITQNIEKLRVEVQKFEGWLAEVE 77

Src Homology 3 domain of Cdc42-Interacting Protein 4; This subfamily is composed of Cdc42-Interacting Protein 4 (CIP4), Formin Binding Protein 17 (FBP17), FormiN Binding Protein 1-Like (FNBP1L), and similar proteins. CIP4 and FNBP1L are Cdc42 effectors that bind Wiskott-Aldrich syndrome protein (WASP) and function in endocytosis. CIP4 and FBP17 bind to the Fas ligand and may be implicated in the inflammatory response. CIP4 may also play a role in phagocytosis. It functions downstream of Cdc42 in PDGF-dependent actin reorganization and cell migration, and also regulates the activity of PDGFRbeta. It uses Src as a substrate in regulating the invasiveness of breast tumor cells. CIP4 may also play a role in the pathogenesis of Huntington's disease. Members of this subfamily typically contain an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs) domain, a central Cdc42-binding HR1 domain, and a C-terminal SH3 domain. The SH3 domain of CIP4 associates with Gapex-5, a Rab31 GEF. 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 663434119 542 HCKAIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRARRQNGEEGYVPTSYIDV 596
Cdd:cd11911    1 TCTALYDFDGTSEGTLSMEEGEILLVLEEDGGDGWTRVRKNNGDEGYVPTSYIEV 55

Src Homology 3 domain of Cdc42-Interacting Protein 4, Bzz1 and similar domains; This subfamily is composed of Cdc42-Interacting Protein 4 (CIP4) and similar proteins such as Formin Binding Protein 17 (FBP17) and FormiN Binding Protein 1-Like (FNBP1L), as well as yeast Bzz1 (or Bzz1p). CIP4 and FNBP1L are Cdc42 effectors that bind Wiskott-Aldrich syndrome protein (WASP) and function in endocytosis. CIP4 and FBP17 bind to the Fas ligand and may be implicated in the inflammatory response. CIP4 may also play a role in phagocytosis. Bzz1 is also a WASP/Las17-interacting protein involved in endocytosis and trafficking to the vacuole. It physically interacts with type I myosins and functions in the early steps of endocytosis. Members of this subfamily contain an N-terminal F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs) domain as well as at least one C-terminal SH3 domain. Bzz1 contains a second SH3 domain at the C-terminus. 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 663434119 542 HCKAIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRARRQNGEEGYVPTSYIDV 596
Cdd:cd11777    1 ECKALYAFVGSSEGTISMTEGEKLSLVEEDKGDGWTRVRRDTGEEGYVPTSYIRI 55

The Extended FES-CIP4 Homology (FCH) or F-BAR (FCH and Bin/Amphiphysin/Rvs) domain, a dimerization module that binds and bends membranes; F-BAR domains are dimerization modules that bind and bend membranes and are found in proteins involved in membrane dynamics and actin reorganization. F-BAR domain containing proteins, also known as Pombe Cdc15 homology (PCH) family proteins, include Fes and Fer tyrosine kinases, PACSINs/Syndapins, FCHO, PSTPIP, CIP4-like proteins and srGAPs. Many members also contain an SH3 domain and play roles in endocytosis. F-BAR domains form banana-shaped dimers with a positively-charged concave surface that binds to negatively-charged lipid membranes. They can induce membrane deformation in the form of long tubules. These tubules have diameters larger than those observed with N-BARs. The F-BAR domains of some members such as NOSTRIN and Rgd1 are important for the subcellular localization of the protein.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119  10 QFDSLDKHTQWGIDFLERYAKFVKERIEIEQNYAKQLRNLVKKYCPKRSSKDeeprfTSCVAFFNILNELNDYAGQ-REV 88
Cdd:cd07610    1 GFELLEKRTELGLDLLKDLREFLKKRAAIEEEYAKNLQKLAKKFSKKPESGK-----TSLGTSWNSLREETESAATvHEE 75

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119  89 VAEEMAHRVYGELMRYAHDLKTERKMHLQEGRKAQQYLDMCWKqmdNSKKKFERECREAEKAQQSY--ERLDNDTNATKA 166
Cdd:cd07610   76 LSEKLSQLIREPLEKVKEDKEQARKKELAEGEKLKKKLQELWA---KLAKKADEEYREQVEKLNPAqsEYEEEKLNKIQA 152

                        170       180       190       200
                 ....*....|....*....|....*....|....*....|....*
gi 663434119 167 DvekaKQQLNLRTHMADENKNEYAaqlqNFNGEQHKHFYVVIPQI 211
Cdd:cd07610  153 E----QEREEERLEILKDNLKNYI----NAIKEIPQKIQQELEQS 189

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

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 663434119 544 KAIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRARRQNGEEGYVPTSYIDV 596
Cdd:cd11912    3 KVLYDYTASGDDEVSISEGEEVTVLEPDDGSGWTKVRNGSGEEGLVPTSYIEI 55

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

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....
gi 663434119 543 CKAIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRARRQNGEEGYVPTSYIDV 596
Cdd:cd11763    2 VRALYDFDSQPSGELSLRAGEVLTITRQDVGDGWLEGRNSRGEVGLFPSSYVEI 55

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 663434119 542 HCKAIYPFDGHNEGTLAMKEGEVLYIIEEDkGDGWTRARRQNGEEGYVPTSY 593
Cdd:cd00174    1 YARALYDYEAQDDDELSFKKGDIITVLEKD-DDGWWEGELNGGREGLFPANY 51

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 663434119  544 KAIYPFDGHNEGTLAMKEGEVLYIIeEDKGDGWTRARRQNGEEGYVPT 591
Cdd:pfam00018   1 VALYDYTAQEPDELSFKKGDIIIVL-EKSEDGWWKGRNKGGKEGLIPS 47

Third Src Homology 3 domain of Nck adaptor proteins; This group contains the third SH3 domain of Nck, the first SH3 domain of Caenorhabditis elegans Ced-2 (Cell death abnormality protein 2), and similar domains. 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 third SH3 domain of Nck appears to prefer ligands with a PxAPxR motif. SH3 domains are protein interaction domains that usually bind to proline-rich ligands with moderate affinity and selectivity, preferentially a PxxP motif. Ced-2 is a cell corpse engulfment protein that interacts with Ced-5 in a pathway that regulates the activation of Ced-10, a Rac small GTPase.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 663434119 545 AIYPFDGHNEGTLAMKEGEVLYIIEEDKGD-GWTRARRQNGEEGYVPTSYIDV 596
Cdd:cd11767    4 ALYPFTGENDEELSFEKGERLEIIEKPEDDpDWWKARNALGTTGLVPRNYVEV 56

Src Homology 3 domain of Nephrocystin (or Nephrocystin-1); Nephrocystin contains an SH3 domain involved in signaling pathways that regulate cell adhesion and cytoskeletal organization. It is a protein that in humans is associated with juvenile nephronophthisis, an inherited kidney disease characterized by renal fibrosis that lead to chronic renal failure in children. It is localized in cell-cell junctions in renal duct cells, and is known to interact with Ack1, an activated Cdc42-associated kinase. 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 663434119 543 CKAIYPFDGHNEGTLAMKEGEVLYIIEEdKGDGWTRARRQNGEEGYVPTSYIDV 596
Cdd:cd11770    2 YEALSDFQAEQEGDLSFKKGEVLRIISK-RADGWWLAENSKGNRGLVPKTYLKV 54

Src homology 3 domain of Type I fungal Myosins; Type I myosins (myosin-I) are actin-dependent motors in endocytic actin structures and actin patches. They play roles in membrane traffic in endocytic and secretory pathways, cell motility, and mechanosensing. Saccharomyces cerevisiae has two myosins-I, Myo3 and Myo5, which are involved in endocytosis and the polarization of the actin cytoskeleton. Myosin-I contains an N-terminal actin-activated ATPase, a phospholipid-binding TH1 (tail homology 1) domain, and a C-terminal extension which includes an F-actin-binding TH2 domain, an SH3 domain, and an acidic peptide that participates in activating the Arp2/3complex. The SH3 domain of myosin-I is required for myosin-I-induced actin polymerization. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 663434119 543 CKAIYPFDGHNEGTLAMKEGEVLYIIEEDkGDGWTRARRQNG-EEGYVPTSYI 594
Cdd:cd11858    2 YKALYDFAGSVANELSLKKDDIVYIVQKE-DNGWWLAKKLDEsKEGWVPAAYL 53

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 663434119 545 AIYPFDGHNEGTLAMKEGEVLYIIEeDKGDGWTRARRQNGEEGYVPTSYI 594
Cdd:cd11768    4 ALYDFQPIEPGDLPLEKGEEYVVLD-DSNEHWWRARDKNGNEGYIPSNYV 52

Src Homology 3 domain of Sorting nexin 18; SNX18 is localized to peripheral endosomal structures, and acts in a trafficking pathway that is clathrin-independent but relies on AP-1 and PACS1. It binds FIP5 and is required for apical lumen formation. It may also play a role in axonal elongation. SNXs are Phox homology (PX) domain containing proteins that are involved in regulating membrane traffic and protein sorting in the endosomal system. SNX18 also contains BAR 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 663434119 544 KAIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRARRQNGEEGYVPTSYIDV 596
Cdd:cd11897    3 RALYDFRSENPGEISLREHEVLSLCSEQDIEGWLEGVNSRGDRGLFPASYVEV 55

Src homology 3 domain of Src kinase-like Protein Tyrosine Kinases; Src subfamily members include Src, Lck, Hck, Blk, Lyn, Fgr, Fyn, Yrk, Yes, and Brk. Src (or c-Src) proteins are cytoplasmic (or non-receptor) PTKs which are anchored to the plasma membrane. They contain an N-terminal SH4 domain with a myristoylation site, followed by SH3 and SH2 domains, a tyr kinase domain, and a regulatory C-terminal region containing a conserved tyr. They are activated by autophosphorylation at the tyr kinase domain, but are negatively regulated by phosphorylation at the C-terminal tyr by Csk (C-terminal Src Kinase). However, Brk lacks the N-terminal myristoylation sites. Src proteins are involved in signaling pathways that regulate cytokine and growth factor responses, cytoskeleton dynamics, cell proliferation, survival, and differentiation. They were identified as the first proto-oncogene products, and they regulate cell adhesion, invasion, and motility in cancer cells, and tumor vasculature, contributing to cancer progression and metastasis. Src kinases are overexpressed in a variety of human cancers, making them attractive targets for therapy. They are also implicated in acute inflammatory responses and osteoclast function. Src, Fyn, Yes, and Yrk are widely expressed, while Blk, Lck, Hck, Fgr, Lyn, and Brk show a limited expression pattern. This subfamily also includes Drosophila Src42A, Src oncogene at 42A (also known as Dsrc41) which accumulates at sites of cell-cell or cell-matrix adhesion, and participates in Drosphila development and wound healing. It has been shown to promote tube elongation in the tracheal system, is essential for proper cell-cell matching during dorsal closure, and regulates cell-cell contacts in developing Drosophila eyes. The SH3 domain of Src kinases contributes to substrate recruitment by binding adaptor proteins/substrates, and regulation of kinase activity through an intramolecular interaction. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 663434119 545 AIYPFDGHNEGTLAMKEGEVLYIIEEDKGDgWTRARRQN-GEEGYVPTSY 593
Cdd:cd11845    4 ALYDYEARTDDDLSFKKGDRLQILDDSDGD-WWLARHLStGKEGYIPSNY 52

The F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs) domain of FCH and double SH3 domains 1 (FCHSD1); F-BAR domains are dimerization modules that bind and bend membranes and are found in proteins involved in membrane dynamics and actin reorganization. FCH and double SH3 domains 1 (FCHSD1) contains an N-terminal F-BAR domain and two SH3 domains at the C-terminus. It has been characterized only in silico, and its biological function is still unknown. F-BAR domains form banana-shaped dimers with a positively-charged concave surface that binds to negatively-charged lipid membranes. They can induce membrane deformation in the form of long tubules.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119   9 DQFDSLDKHTQWGIDFLERYAKFVKERIEIEQNYAKQLRNLVKKYCPK--RSSKDEEPRFTSCVAFFNILNELNDYAGQR 86
Cdd:cd07678    5 EQLSILQTKQQRDAELLEDIRSYSKQRAAIEREYGQALQRLASQFLKRdwHRGGNETEMDRSVRTVWGAWREGTAATGQG 84

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119  87 EVVAEEmAHRVYGELMRYAHDLKTER--KMHLQEGRKAQQYLDMCWKQMDNSKKKFERECREAEKAQQS-------YERL 157
Cdd:cd07678   85 RVTRLE-AYRRLRDEAGKTGRSAKEQvlKKSTEQLQKAQAELLETVKELSKSKKLYGQLERVSEVAKEKaadvearLNKS 163

                        170       180       190       200       210       220
                 ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 663434119 158 DNDTNATKADVEKAKQQLNlrTHMADENK------NEYAAQLQNFNGEQHKHFYVVIPQIYKQL 215
Cdd:cd07678  164 DHGIFHSKASLQKLSAKFS--AQSAEYSQqlqaarNEYLLNLVAANAHLDHYYQEELPAIMKAL 225

Variant SH3 domain;

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|.
gi 663434119  545 AIYPFDGHNEGTLAMKEGEVLYIIEEDkGDGWTRARRqNGEEGYVPTSYID 595
Cdd:pfam14604   1 ALYPYEPKDDDELSLQRGDVITVIEES-EDGWWEGIN-TGRTGLVPANYVE 49

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

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|.
gi 663434119 545 AIYPFDGHNEGTLAMKEGEVLYIIEEDKGdGWTRARRqNGEEGYVPTSYID 595
Cdd:cd11856    4 AIADYEAQGDDEISLQEGEVVEVLEKNDS-GWWYVRK-GDKEGWVPASYLE 52

The F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs) domain of Proline-Serine-Threonine Phosphatase-Interacting Protein 2; F-BAR domains are dimerization modules that bind and bend membranes and are found in proteins involved in membrane dynamics and actin reorganization. Proline-Serine-Threonine Phosphatase-Interacting Protein 2 (PSTPIP2), also known as Macrophage Actin-associated tYrosine Phosphorylated protein (MAYP), is mostly expressed in hematopoietic cells but is also expressed in the brain. It is involved in regulating cell adhesion and motility. Mutations in the gene encoding murine PSTPIP2 can cause autoinflammatory disorders such as chronic multifocal osteomyelitis and macrophage autoinflammatory disease. PSTPIP2 contains an N-terminal F-BAR domain and lacks the PEST motifs and SH3 domain that are found in PSTPIP1. F-BAR domains form banana-shaped dimers with a positively-charged concave surface that binds to negatively-charged lipid membranes. They can induce membrane deformation in the form of long tubules.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119  11 FDSLDKHTQWGIDFLERYAKFVKERIEIEQNYAKQLRNLVKKYCPKRSSKDEEPRftscvaffnilnELNDYAGQREVVA 90
Cdd:cd07672    7 YDCIIQHLNDGRKNCKEFEDFLKERASIEEKYGKELLNLSKKKPCGQTEINTLKR------------SLDVFKQQIDNVG 74

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119  91 EemAHRVYGELMR-YAHDLKTERKMHLQEGRKAQQYLD-------MCWKQMDNSKKKFERECREAEKAQQSYERLDNDTN 162
Cdd:cd07672   75 Q--SHIQLAQTLRdEAKKMEDFRERQKLARKKIELIMDaihkqraMQFKKTMESKKNYEQKCRDKDEAEQAVNRNANLVN 152

                        170
                 ....*....|..
gi 663434119 163 ATKADVEKAKQQ 174
Cdd:cd07672  153 VKQQEKLFAKLA 164

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 663434119 544 KAIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRARRQNGEEGYVPTSYID 595
Cdd:cd11998    4 RALYDYDGQEQDELSFKAGDELTKLEDEDEQGWCKGRLDSGQVGLYPANYVE 55

First 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. 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 663434119 543 CKAIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRARRQN-----GEEGYVPTSY 593
Cdd:cd11773    2 YKALYDYEPQTEDELTIQEDDILYLLEKSDDDWWKVKLKVNssdddEPVGLVPATY 57

Src Homology 3 domain of Bruton's tyrosine kinase; BTK is a cytoplasmic (or nonreceptor) tyr kinase containing Src homology protein interaction domains (SH3, SH2) N-terminal to the catalytic tyr kinase domain. It also contains an N-terminal pleckstrin homology (PH) domain, which binds the products of PI3K and allows membrane recruitment and activation, and the Tec homology (TH) domain with proline-rich and zinc-binding regions. Btk is expressed in B-cells, and a variety of myeloid cells including mast cells, platelets, neutrophils, and dendrictic cells. It interacts with a variety of partners, from cytosolic proteins to nuclear transcription factors, suggesting a diversity of functions. Stimulation of a diverse array of cell surface receptors, including antigen engagement of the B-cell receptor (BCR), leads to PH-mediated membrane translocation of Btk and subsequent phosphorylation by Src kinase and activation. Btk plays an important role in the life cycle of B-cells including their development, differentiation, proliferation, survival, and apoptosis. Mutations in Btk cause the primary immunodeficiency disease, X-linked agammaglobulinaemia (XLA) in humans. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 663434119 545 AIYPFDGHNEGTLAMKEGEVlYIIEEDKGDGWTRARRQNGEEGYVPTSYI 594
Cdd:cd11906    5 ALYDYTPMNAQDLQLRKGEE-YVILEESNLPWWRARDKNGREGYIPSNYV 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.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....
gi 663434119 543 CKAIYPFDGHNEGTLAMKEGEVLYIIEEDKgDGWTRArRQNGEEGYVPTSYIDV 596
Cdd:cd11823    2 CKALYSYTANREDELSLQPGDIIEVHEKQD-DGWWLG-ELNGKKGIFPATYVEE 53

The F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs) domain of Slit-Robo GTPase Activating Proteins; F-BAR domains are dimerization modules that bind and bend membranes and are found in proteins involved in membrane dynamics and actin reorganization. Slit-Robo GTPase Activating Proteins (srGAPs) are Rho GAPs that interact with Robo1, the transmembrane receptor of Slit proteins. Slit proteins are secreted proteins that control axon guidance and the migration of neurons and leukocytes. Vertebrates contain three isoforms of srGAPs, all of which are expressed during embryonic and early development in the nervous system but with different localization and timing. srGAPs contain an N-terminal F-BAR domain, a Rho GAP domain, and a C-terminal SH3 domain. F-BAR domains form banana-shaped dimers with a positively-charged concave surface that binds to negatively-charged lipid membranes. They can induce membrane deformation in the form of long tubules.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119   5 TELWDQFDSLDKHTQWGIDFLERYAKFVKERIEIEQNYAKQLRNLVKKYCPK----RSSKDEEPRFTSCVAFFNILNE-- 78
Cdd:cd07656    1 QQLSEQLKCLDLRTEAQVQLLADLQDYFRRRAEIELEYSRSLEKLADRFSSKhkneKSKREDWSLLSPVNCWNTLLVQtk 80

                         90       100       110       120       130       140       150       160
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 663434119  79 --------LND-YAG---QREVVAEEMAHRVY-----------GELMRYAHDLKTERK---MHLQEGRKAQQYLdmcwKQ 132
Cdd:cd07656   81 qesrdhstLSDiYSNnlvQRLGQMSEDLQRISkkcreigsqlhDELLRVLNELQTAMKtyhTYHAESKSAERKL----KE 156

                        170       180       190       200       210       220       230
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 663434119 133 MDNSKKKFERECREAEKAQQSYERLDNDTNATKADVEKAKQQlnlrthmADENKNEYAAQLQNFNGEQHKHF 204
Cdd:cd07656  157 AEKQEEKQEQSPEKKLERSRSSKKIEKEVEKRQAKYSEAKLK-------CTKARNEYLLNLAAANATIHKYF 221

Src homology 3 domain of Blk Protein Tyrosine Kinase; Blk is a member of the Src subfamily of proteins, which are cytoplasmic (or non-receptor) PTKs. It is expressed specifically in B-cells and is involved in pre-BCR (B-cell receptor) signaling. Src kinases contain an N-terminal SH4 domain with a myristoylation site, followed by SH3 and SH2 domains, a tyr kinase domain, and a regulatory C-terminal region containing a conserved tyr. They are activated by autophosphorylation at the tyr kinase domain, but are negatively regulated by phosphorylation at the C-terminal tyr by Csk (C-terminal Src Kinase). The SH3 domain of Src kinases contributes to substrate recruitment by binding adaptor proteins/substrates, and regulation of kinase activity through an intramolecular interaction. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 663434119 545 AIYPFDGHNEGTLAMKEGEVLYIIEEDkGDGWTRARRQNGEEGYVPTSYI 594
Cdd:cd12009    4 AQYDFVPSNERDLQLKKGEKLQVLKSD-GEWWLAKSLTTGKEGYIPSNYV 52

Src homology 3 domain of Src Protein Tyrosine Kinase; Src (or c-Src) is a cytoplasmic (or non-receptor) PTK and is the vertebrate homolog of the oncogenic protein (v-Src) from Rous sarcoma virus. Together with other Src subfamily proteins, it is involved in signaling pathways that regulate cytokine and growth factor responses, cytoskeleton dynamics, cell proliferation, survival, and differentiation. Src also play a role in regulating cell adhesion, invasion, and motility in cancer cells, and tumor vasculature, contributing to cancer progression and metastasis. Elevated levels of Src kinase activity have been reported in a variety of human cancers. Several inhibitors of Src have been developed as anti-cancer drugs. Src is also implicated in acute inflammatory responses and osteoclast function. Src kinases contain an N-terminal SH4 domain with a myristoylation site, followed by SH3 and SH2 domains, a tyr kinase domain, and a regulatory C-terminal region containing a conserved tyr. They are activated by autophosphorylation at the tyr kinase domain, but are negatively regulated by phosphorylation at the C-terminal tyr by Csk (C-terminal Src Kinase). The SH3 domain of Src kinases contributes to substrate recruitment by binding adaptor proteins/substrates, and regulation of kinase activity through an intramolecular interaction. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 663434119 545 AIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRARRQNGEEGYVPTSYI 594
Cdd:cd12008    4 ALYDYESRTETDLSFKKGERLQIVNNTEGDWWLAHSLTTGQTGYIPSNYV 53

Src homology 3 domain of Fyn and Yrk Protein Tyrosine Kinases; Fyn and Yrk (Yes-related kinase) are members of the Src subfamily of proteins, which are cytoplasmic (or non-receptor) PTKs. Fyn, together with Lck, plays a critical role in T-cell signal transduction by phosphorylating ITAM (immunoreceptor tyr activation motif) sequences on T-cell receptors, ultimately leading to the proliferation and differentiation of T-cells. In addition, Fyn is involved in the myelination of neurons, and is implicated in Alzheimer's and Parkinson's diseases. Yrk has been detected only in chickens. It is primarily found in neuronal and epithelial cells and in macrophages. It may play a role in inflammation and in response to injury. Src kinases contain an N-terminal SH4 domain with a myristoylation site, followed by SH3 and SH2 domains, a tyr kinase domain, and a regulatory C-terminal region containing a conserved tyr. They are activated by autophosphorylation at the tyr kinase domain, but are negatively regulated by phosphorylation at the C-terminal tyr by Csk (C-terminal Src Kinase). The SH3 domain of Src kinases contributes to substrate recruitment by binding adaptor proteins/substrates, and regulation of kinase activity through an intramolecular interaction. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|
gi 663434119 545 AIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRARRQNGEEGYVPTSYI 594
Cdd:cd12006    5 ALYDYEARTEDDLSFHKGEKFQILNSSEGDWWEARSLTTGETGYIPSNYV 54

Src Homology 3 domain of Interleukin-2-inducible T-cell Kinase; ITK (also known as Tsk or Emt) is a cytoplasmic (or nonreceptor) tyr kinase containing Src homology protein interaction domains (SH3, SH2) N-terminal to the catalytic tyr kinase domain. It also contains an N-terminal pleckstrin homology (PH) domain, which binds the products of PI3K and allows membrane recruitment and activation, and the Tec homology (TH) domain, which contains proline-rich and zinc-binding regions. ITK is expressed in T-cells and mast cells, and is important in their development and differentiation. Of the three Tec kinases expressed in T-cells, ITK plays the predominant role in T-cell receptor (TCR) signaling. It is activated by phosphorylation upon TCR crosslinking and is involved in the pathway resulting in phospholipase C-gamma1 activation and actin polymerization. It also plays a role in the downstream signaling of the T-cell costimulatory receptor CD28, the T-cell surface receptor CD2, and the chemokine receptor CXCR4. In addition, ITK is crucial for the development of T-helper(Th)2 effector responses. 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 663434119 545 AIYPFDGHNEGTLAMKEGEVLYIIEEDKgDGWTRARRQNGEEGYVPTSYI 594
Cdd:cd11908    5 ALYDYQTNDPQELALRYNEEYHLLDSSE-IHWWRVQDKNGHEGYVPSSYL 53

N-terminal Src homology 3 domain of Growth factor receptor-bound protein 2; GRB2 is a critical signaling molecule that regulates the Ras pathway by linking tyrosine kinases to the Ras guanine nucleotide releasing protein Sos (son of sevenless), which converts Ras to the active GTP-bound state. It is ubiquitously expressed in all tissues throughout development and is important in cell cycle progression, motility, morphogenesis, and angiogenesis. In lymphocytes, GRB2 is associated with antigen receptor signaling components. GRB2 contains an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. Its N-terminal SH3 domain binds to Sos and Sos-derived proline-rich peptides. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 663434119 545 AIYPFDGHNEGTLAMKEGEVLYIIEEDKGDGWTRArRQNGEEGYVPTSYIDV 596
Cdd:cd11946    5 AKYDFKATADDELSFKRGDILKVLNEECDQNWYKA-ELNGKDGFIPKNYIEM 55

N-terminal Src homology 3 domain of GRB2-related adaptor protein 2; GRAP2 is also called GADS (GRB2-related adapter downstream of Shc), GrpL, GRB2L, Mona, or GRID (Grb2-related protein with insert domain). It is expressed specifically in the hematopoietic system. It plays an important role in T cell receptor (TCR) signaling by promoting the formation of the SLP-76:LAT complex, which couples the TCR to the Ras pathway. It also have roles in antigen-receptor and tyrosine kinase mediated signaling. GRAP2 is unique from other GRB2-like adaptor proteins in that it can be regulated by caspase cleavage. It contains an N-terminal SH3 domain, a central SH2 domain, and a C-terminal SH3 domain. The N-terminal SH3 domain of the related protein GRB2 binds to Sos and Sos-derived proline-rich peptides. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|...
gi 663434119 544 KAIYPFDGHNEGTLAMKEGEVLYIIEEDkgDGWTRARrQNGEEGYVPTSYIDV 596
Cdd:cd11947    3 RGKFDFTASGEDELSFKKGDVLKILSSD--DIWFKAE-LNGEEGYVPKNFVDI 52