C2 domain of the Regulator Of G-Protein Signaling (RGS) family; This CD contains members of the regulator of G-protein signaling (RGS) family. RGS is a GTPase activating protein which inhibits G-protein mediated signal transduction. The protein is largely cytosolic, but G-protein activation leads to translocation of this protein to the plasma membrane. A nuclear form of this protein has also been described, but its sequence has not been identified. There are multiple alternatively spliced transcript variants in this family with some members having additional domains (ex. PDZ and RGS) downstream of the C2 domain. The C2 domain was first identified in PKC. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  27 GQLKLSIDAQDRVLLLHIIEGKGLMSREPGICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHFFFPVPEEGDQKRL 106
Cdd:cd08685     1 GQLKLSIEGQNRKLTLHVLEAKGLRSTNSGTCNSYVKISLSPDKEVRFRQKTSTVPDSANPLFHETFSFDVNERDYQKRL 80

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|
gi 1720409246 107 LVTVWNRASETRQHTLIGCMSFGVRSLLtPDKEISGWYYL 146
Cdd:cd08685    81 LVTVWNKLSKSRDSGLLGCMSFGVKSIV-NQKEISGWYYL 119

C2 domain of the Regulator Of G-Protein Signaling (RGS) family; This CD contains members of the regulator of G-protein signaling (RGS) family. RGS is a GTPase activating protein which inhibits G-protein mediated signal transduction. The protein is largely cytosolic, but G-protein activation leads to translocation of this protein to the plasma membrane. A nuclear form of this protein has also been described, but its sequence has not been identified. There are multiple alternatively spliced transcript variants in this family with some members having additional domains (ex. PDZ and RGS) downstream of the C2 domain. The C2 domain was first identified in PKC. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  27 GQLKLSIDAQDRVLLLHIIEGKGLMSREPGICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHFFFPVPEEGDQKRL 106
Cdd:cd08685     1 GQLKLSIEGQNRKLTLHVLEAKGLRSTNSGTCNSYVKISLSPDKEVRFRQKTSTVPDSANPLFHETFSFDVNERDYQKRL 80

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|
gi 1720409246 107 LVTVWNRASETRQHTLIGCMSFGVRSLLtPDKEISGWYYL 146
Cdd:cd08685    81 LVTVWNKLSKSRDSGLLGCMSFGVKSIV-NQKEISGWYYL 119

C2 domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  39 VLLLHIIEGKGLMSREP-GICDPYVKVSLipeDSQLPCQTTQIIPDCRDPAFHEHFFFPVPEEGDQKrLLVTVWNRASET 117
Cdd:pfam00168   2 RLTVTVIEAKNLPPKDGnGTSDPYVKVYL---LDGKQKKKTKVVKNTLNPVWNETFTFSVPDPENAV-LEIEVYDYDRFG 77

                          90       100
                  ....*....|....*....|....*....
gi 1720409246 118 RqHTLIGCMSFGVRSLLtPDKEISGWYYL 146
Cdd:pfam00168  78 R-DDFIGEVRIPLSELD-SGEGLDGWYPL 104

Domain present in PSD-95, Dlg, and ZO-1/2; Also called DHR (Dlg homologous region) or GLGF (relatively well conserved tetrapeptide in these domains). Some PDZs have been shown to bind C-terminal polypeptides; others appear to bind internal (non-C-terminal) polypeptides. Different PDZs possess different binding specificities.

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1720409246  188 ITIRRGKDGFGFTIC----CDSPVRVQAVDSGGPAERAGLQQLDTVLQLNERPVEHWKCVELAHEIRSCPSEIILLVWR 262
Cdd:smart00228   5 VELEKGGGGLGFSLVggkdEGGGVVVSSVVPGSPAAKAGLRVGDVILEVNGTSVEGLTHLEAVDLLKKAGGKVTLTVLR 83

Membrane-associated protease RseP, regulator of RpoE activity [Posttranslational modification, protein turnover, chaperones, Transcription];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246 205 SPVRVQAVDSGGPAERAGLQQLDTVLQLNERPVEHWKcvELAHEIRSCP-SEIILLVWR--------VVPQIKPGPDGGV 275
Cdd:COG0750   128 TPPVVGEVVPGSPAAKAGLQPGDRIVAINGQPVTSWD--DLVDIIRASPgKPLTLTVERdgeeltltVTPRLVEEDGVGR 205

                  .
gi 1720409246 276 L 276
Cdd:COG0750   206 I 206

C2 domain of the Regulator Of G-Protein Signaling (RGS) family; This CD contains members of the regulator of G-protein signaling (RGS) family. RGS is a GTPase activating protein which inhibits G-protein mediated signal transduction. The protein is largely cytosolic, but G-protein activation leads to translocation of this protein to the plasma membrane. A nuclear form of this protein has also been described, but its sequence has not been identified. There are multiple alternatively spliced transcript variants in this family with some members having additional domains (ex. PDZ and RGS) downstream of the C2 domain. The C2 domain was first identified in PKC. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  27 GQLKLSIDAQDRVLLLHIIEGKGLMSREPGICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHFFFPVPEEGDQKRL 106
Cdd:cd08685     1 GQLKLSIEGQNRKLTLHVLEAKGLRSTNSGTCNSYVKISLSPDKEVRFRQKTSTVPDSANPLFHETFSFDVNERDYQKRL 80

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|
gi 1720409246 107 LVTVWNRASETRQHTLIGCMSFGVRSLLtPDKEISGWYYL 146
Cdd:cd08685    81 LVTVWNKLSKSRDSGLLGCMSFGVKSIV-NQKEISGWYYL 119

C2 domain in Protein Kinase C (PKC) alpha and gamma; A single C2 domain is found in PKC alpha and gamma. The PKC family of serine/threonine kinases regulates apoptosis, proliferation, migration, motility, chemo-resistance, and differentiation. There are 3 groups: group 1(alpha, betaI, beta II, gamma) which require phospholipids and calcium, group 2 (delta, epsilon, theta, eta) which do not require calcium for activation, and group 3 (xi, iota/lambda) which are atypical and can be activated in the absence of diacylglycerol and calcium. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. Members here have a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  27 GQLKLSIDAQDRVLLLHIIEGKGLMSREP-GICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHFFFPVPEEGDQKR 105
Cdd:cd04026     2 GRIYLKISVKDNKLTVEVREAKNLIPMDPnGLSDPYVKLKLIPDPKNETKQKTKTIKKTLNPVWNETFTFDLKPADKDRR 81

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|.
gi 1720409246 106 LLVTVWNRASETRqHTLIGCMSFGVRSLLtpDKEISGWYYLLGEDLGRTKH 156
Cdd:cd04026    82 LSIEVWDWDRTTR-NDFMGSLSFGVSELI--KMPVDGWYKLLNQEEGEYYN 129

C2 domain;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  39 VLLLHIIEGKGLMSREP-GICDPYVKVSLipeDSQLPCQTTQIIPDCRDPAFHEHFFFPVPEEGDQKrLLVTVWNRASET 117
Cdd:pfam00168   2 RLTVTVIEAKNLPPKDGnGTSDPYVKVYL---LDGKQKKKTKVVKNTLNPVWNETFTFSVPDPENAV-LEIEVYDYDRFG 77

                          90       100
                  ....*....|....*....|....*....
gi 1720409246 118 RqHTLIGCMSFGVRSLLtPDKEISGWYYL 146
Cdd:pfam00168  78 R-DDFIGEVRIPLSELD-SGEGLDGWYPL 104

canonical PDZ domain; Canonical PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain. PDZ domains usually bind to short specific peptide sequences located at the C-terminal end of their partner proteins known as PDZ binding motifs. These domains can also interact with internal peptide motifs and certain lipids, and can take part in a head-to-tail oligomerization with other PDZ domains. The PDZ superfamily includes canonical PDZ domains as well as those with circular permutations and domain swapping mediated by beta-strands. The canonical PDZ domain contains six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2), arranged in the order: beta-strands A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1720409246 188 ITIRRGK-DGFGFTIC----CDSPVRVQAVDSGGPAERAG-LQQLDTVLQLNERPVEHWKCVELAHEIRSCPSEIILLV 260
Cdd:cd00136     2 VTLEKDPgGGLGFSIRggkdGGGGIFVSRVEPGGPAARDGrLRVGDRILEVNGVSLEGLTHEEAVELLKSAGGEVTLTV 80

PDZ domain of rhophilin-1, rhophilin-2, and related domains; PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain of rhophilin-1, rhophilin-2, and related domains. Rhophilin-1 (RHPN1, also known as GTP-Rho-binding protein 1) and rhophilin-2 (RHPN2, also known as GTP-Rho-binding protein 2) are Rho-GTP binding proteins involved in cytoskeletal dynamics. Rhophilin-2 inhibits RhoA's activity to induce F-actin stress fibers. PDZ domains usually bind in a sequence-specific manner to short peptide sequences located at the C-terminal end of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains as well as those with circular permutations and domain swapping mediated by beta-strands. This rhophilin-like family domain is a canonical PDZ domain containing six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2), arranged in the order: beta-strands A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1720409246 188 ITIRRGKDGFGFTICCDSPVRVQAVDSGGPAERAGLQQLDTVLQLNERPVEHWKCVELAHEIRSCPSEIILLvwRVV 264
Cdd:cd06712     4 VHLTKEEGGFGFTLRGDSPVQVASVDPGSCAAEAGLKEGDYIVSVGGVDCKWSKHSEVVKLLKSAGEEGLEL--QVV 78

Domain present in PSD-95, Dlg, and ZO-1/2; Also called DHR (Dlg homologous region) or GLGF (relatively well conserved tetrapeptide in these domains). Some PDZs have been shown to bind C-terminal polypeptides; others appear to bind internal (non-C-terminal) polypeptides. Different PDZs possess different binding specificities.

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 1720409246  188 ITIRRGKDGFGFTIC----CDSPVRVQAVDSGGPAERAGLQQLDTVLQLNERPVEHWKCVELAHEIRSCPSEIILLVWR 262
Cdd:smart00228   5 VELEKGGGGLGFSLVggkdEGGGVVVSSVVPGSPAAKAGLRVGDVILEVNGTSVEGLTHLEAVDLLKKAGGKVTLTVLR 83

PDZ domain of DEP domain-containing mTOR-interacting protein (DEPTOR), and related domains; PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain of DEPTOR, and related domains. DEPTOR (also known as DEP domain-containing protein 6, DEP6) is a regulatory protein of mTOR signaling; it is a negative regulator of both the mTORC1 and mTORC2 signaling pathways. DEPTOR's PDZ domain binds to mTOR's FAT domain to suppress mTOR's kinase activity. The DEPTOR PDZ domain also binds lysine-specific demethylase 4A (KDM4A), leucine-rich repeat containing 4 (LRRC4), p38gamma, and major intrinsically disordered Notch2-binding receptor 1 (MINAR1, also known as Ubtor). DEPTOR also interacts with salt-inducible kinase 3 (SIK3). PDZ domains usually bind in a sequence-specific manner to short peptide sequences located at the C-terminal end of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains as well as those with circular permutations and domain swapping mediated by beta-strands. This DEPTOR-like family domain is a canonical PDZ domain containing six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2), arranged in the order: beta-strands A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1720409246 188 ITIRRGKDGFGFTICCDSPVRVQAVDSGGPAERAGLQQLDTVLQLNERPVEHWKCVELAHEIRSCPSEIILLV 260
Cdd:cd23067     2 LTIVGDAVGWGFVVRGSKPCHIQAVDPSGPAAAAGMKVCQFIVSVNGLNVLHMDHRTVSNLILTGPRTIVMEV 74

C2 domain second repeat present in Synaptotagmin; Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. There are several classes of Synaptotagmins. Previously all synaptotagmins were thought to be calcium sensors in the regulation of neurotransmitter release and hormone secretion, but it has been shown that not all of them bind calcium. Of the 17 identified synaptotagmins only 8 bind calcium (1-3, 5-7, 9, 10). The function of the two C2 domains that bind calcium are: regulating the fusion step of synaptic vesicle exocytosis (C2A) and binding to phosphatidyl-inositol-3,4,5-triphosphate (PIP3) in the absence of calcium ions and to phosphatidylinositol bisphosphate (PIP2) in their presence (C2B). C2B also regulates also the recycling step of synaptic vesicles. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the second C2 repeat, C2B, and has a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  28 QLKLSIDAQDRVLLLHIIEGKGLM-SREPGICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHFFFPVPEEG-DQKR 105
Cdd:cd00276     4 LLSLSYLPTAERLTVVVLKARNLPpSDGKGLSDPYVKVSLLQGGKKLKKKKTSVKKGTLNPVFNEAFSFDVPAEQlEEVS 83

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|..
gi 1720409246 106 LLVTVWNRaSETRQHTLIGCMSFGVRS-----------LLTPDKEISGWYYL 146
Cdd:cd00276    84 LVITVVDK-DSVGRNEVIGQVVLGPDSggeelehwnemLASPRKPIARWHKL 134

PDZ domain of FERM and PDZ domain-containing protein 1 (FRMPD1), FRMPD3, FRMPD4, and related domains; PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain of FRMPD1, FRMPD3, FRMPD4, and related domains. FRMPD1 (also known as FERM domain-containing protein 2, FRMD2), inhibits the malignant phenotype of lung cancer by activating the Hippo pathway via interaction with WWC3; the FRMPD1 PDZ domain binds WWC3. FRMPD3 is a target gene of the neuron-specific transcription factor NPAS4 that is involved in synaptic plasticity. FRMPD4 (also known as PDZ domain-containing protein 10, PDZD10, PDZK10, PSD-95-interacting regulator of spine morphogenesis, and Preso) regulates dendritic spine morphogenesis, and mGluR1/5 signaling; the FRMPD4 PDZ domain binds PAK-interacting exchange factor-beta (betaPix). PDZ domains usually bind in a sequence-specific manner to short peptide sequences located at the C-terminal end of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains as well as those with circular permutations and domain swapping mediated by beta-strands. This FRMPD1,3,4-like family domain is a canonical PDZ domain containing six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2), arranged in the order: beta-strands A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1720409246 187 QITIRRgkD---GFGFTICCDSPVRVQAVDSGGPAErAGLQQLDTVLQLNERPVEHWKCVELAHEIRSCPSEIILLV 260
Cdd:cd06769     1 TVEIQR--DavlGFGFVAGSERPVVVRSVTPGGPSE-GKLLPGDQILKINNEPVEDLPRERVIDLIRECKDSIVLTV 74

PDZ domain 1 of delphilin (L-delphilin isoform), and related domains; PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain 1 of delphilin (also known as glutamate receptor, ionotropic, delta 2-interacting protein 1, L-delphilin). Delphilin, a postsynaptic protein which is selectively expressed at cerebellar Purkinje cells, links the glutamate receptor delta 2 subunit (GluRdelta2) with the actin cytoskeleton and various signaling molecules. Two alternatively spliced isoforms of delphilin have been characterized: L-delphilin has two PDZ domains, PDZ1 and PDZ2, and S-delphilin has a single PDZ domain (PDZ2). These two isoforms are differently palmitoylated and may be involved in controlling GluRdelta2 signaling in Purkinje cells. PDZ domains usually bind in a sequence-specific manner to short peptide sequences located at the C-terminal end of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains as well as those with circular permutations and domain swapping mediated by beta-strands. This delphilin-like family PDZ1 domain is a canonical PDZ domain containing six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2), arranged in the order: beta-strands A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1720409246 197 FGFTICCDSPVRVQAVDSGGPAERAGLQQLDTVLQLNERPVEHWKC---VELAHEIRSCPSEI 256
Cdd:cd06743    11 FGFSIGGSGPCYILSVEEGSSAHAAGLQPGDQILELDGQDVSSLSCeaiIALARRCPSVPPSL 73

C2 domain second repeat in Munc13 (mammalian uncoordinated)-like proteins; C2-like domains are thought to be involved in phospholipid binding in a Ca2+ independent manner in both Unc13 and Munc13. Caenorabditis elegans Unc13 has a central domain with sequence similarity to PKC, which includes C1 and C2-related domains. Unc13 binds phorbol esters and DAG with high affinity in a phospholipid manner. Mutations in Unc13 results in abnormal neuronal connections and impairment in cholinergic neurotransmission in the nematode. Munc13 is the mammalian homolog which are expressed in the brain. There are 3 isoforms (Munc13-1, -2, -3) and are thought to play a role in neurotransmitter release and are hypothesized to be high-affinity receptors for phorbol esters. Unc13 and Munc13 contain both C1 and C2 domains. There are two C2 related domains present, one central and one at the carboxyl end. Munc13-1 contains a third C2-like domain. Munc13 interacts with syntaxin, synaptobrevin, and synaptotagmin suggesting a role for these as scaffolding proteins. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the third C2 repeat, C2C, and has a type-II topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  25 TFGQL--KLSIDAQDRVLLLHIIEGKGLMSREP-GICDPYVKVSLIPED--SQLPCQTTQIIPDCRDPAFHEHFFFPVPE 99
Cdd:cd04009     1 PYGVLtvKAYYRASEQSLRVEILNARNLLPLDSnGSSDPFVKVELLPRHlfPDVPTPKTQVKKKTLFPLFDESFEFNVPP 80

                          90
                  ....*....|....
gi 1720409246 100 EGDQKR---LLVTV 110
Cdd:cd04009    81 EQCSVEgalLLFTV 94

C2A domain first repeat present in Synaptotagmin 8; Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. Previously all synaptotagmins were thought to be calcium sensors in the regulation of neurotransmitter release and hormone secretion, but it has been shown that not all of them bind calcium. Of the 17 identified synaptotagmins only 8 bind calcium (1-3, 5-7, 9, 10). The function of the two C2 domains that bind calcium are: regulating the fusion step of synaptic vesicle exocytosis (C2A) and binding to phosphatidyl-inositol-3,4,5-triphosphate (PIP3) in the absence of calcium ions and to phosphatidylinositol bisphosphate (PIP2) in their presence (C2B). C2B also regulates also the recycling step of synaptic vesicles. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the first C2 repeat, C2A, and has a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  27 GQLKLSI--DAQDRVLLLHIIEGKGLMSRE-PGICDPYVKVSLIPEDSQlPCQtTQIIPDCRDPAFHEHFFFPVPEEGDQ 103
Cdd:cd08387     3 GELHFSLeyDKDMGILNVKLIQARNLQPRDfSGTADPYCKVRLLPDRSN-TKQ-SKIHKKTLNPEFDESFVFEVPPQELP 80

                  ....
gi 1720409246 104 KRLL 107
Cdd:cd08387    81 KRTL 84

PDZ domain; PDZ domains are found in diverse signaling proteins.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246 187 QITIRRGKDG-FGFTI-----CCDSPVRVQAVDSGGPAERAGLQQLDTVLQLNERPVEHWKCVELAHEIRSCPSEIILLV 260
Cdd:pfam00595   1 QVTLEKDGRGgLGFSLkggsdQGDPGIFVSEVLPGGAAEAGGLKVGDRILSINGQDVENMTHEEAVLALKGSGGKVTLTI 80

                  .
gi 1720409246 261 W 261
Cdd:pfam00595  81 L 81

C2 domain first repeat present in Synaptotagmin-like proteins; All Slp members basically share an N-terminal Slp homology domain (SHD) and C-terminal tandem C2 domains (named the C2A domain and the C2B domain) with the SHD and C2 domains being separated by a linker sequence of various length. Slp1/JFC1 and Slp2/exophilin 4 promote granule docking to the plasma membrane. Additionally, their C2A domains are both Ca2+ independent, unlike the case in Slp3 and Slp4/granuphilin in which their C2A domains are Ca2+ dependent. It is thought that SHD (except for the Slp4-SHD) functions as a specific Rab27A/B-binding domain. In addition to Slps, rabphilin, Noc2, and Munc13-4 also function as Rab27-binding proteins. It has been demonstrated that Slp3 and Slp4/granuphilin promote dense-core vesicle exocytosis. Slp5 mRNA has been shown to be restricted to human placenta and liver suggesting a role in Rab27A-dependent membrane trafficking in specific tissues. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the first C2 repeat, C2A, and has a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  28 QLKLSIDAQDRVLLLHIIEGKGLMSREPG--ICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHFFFPVPE-EGDQK 104
Cdd:cd08521     4 EFSLSYNYKTGSLEVHIKECRNLAYADEKkkRSNPYVKVYLLPDKSKQSKRKTSVKKNTTNPVFNETLKYHISKsQLETR 83

                  ....*...
gi 1720409246 105 RLLVTVWN 112
Cdd:cd08521    84 TLQLSVWH 91

PDZ domain 2 of membrane-associated guanylate kinase inverted 1 (MAGI-1), MAGI-2, and MAGI-3, and related domains; PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain 2 of MAGI1, 2, 3 (MAGI is also known as Membrane-associated guanylate kinase, WW and PDZ domain-containing protein) and related domains. MAGI proteins have been implicated in the control of cell migration and invasion through altering the activity of phosphatase and tensin homolog (PTEN) and modulating Akt signaling. Four MAGI proteins have been identified (MAGI1-3 and MAGIX). MAGI1-3 have 6 PDZ domains and bind to the C-terminus of PTEN via their PDZ2 domain. MAGIX has a single PDZ domain that is related to MAGI1-3 PDZ domain 5. Other binding partners for MAGI1 include JAM4, C-terminal tail of high risk HPV-18 E6, megalin, TRAF6, Kir4.1 (basolateral K+ channel subunit), and cadherin 23; for MAGI2, include DASM1, dendrin, axin, beta- and delta-catenin, neuroligin, hyperpolarization-activated cation channels, beta1-adrenergic receptors, NMDA receptor, and TARPs; and for MAGI3 includes LPA2. PDZ domains usually bind in a sequence-specific manner to short peptide sequences located at the C-terminal end of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains as well as those with circular permutations and domain swapping mediated by beta-strands. This MAGI family PDZ2 domain is a canonical PDZ domain containing six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2); arranged as beta-strands A, -B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246 183 GEKLQITIRRGKDGFGFTIcCDSPV--RV-QAVDSggpaER-AGLQQLDTVLQLNERPVEHWKCVELAHEIRSCP--SEI 256
Cdd:cd06732     1 PELVTVPIVKGPMGFGFTI-ADSPQgqRVkQILDP----QRcRGLQEGDLIVEINGQNVQNLSHAQVVDVLKECPkgSEV 75

                  ....*.
gi 1720409246 257 ILLVWR 262
Cdd:cd06732    76 TLLVQR 81

C2 domain first repeat present in Rabphilin and Double C2 domain; Rabphilin is found neurons and in neuroendrocrine cells, while Doc2 is found not only in the brain but in tissues, including mast cells, chromaffin cells, and osteoblasts. Rabphilin and Doc2s share highly homologous tandem C2 domains, although their N-terminal structures are completely different: rabphilin contains an N-terminal Rab-binding domain (RBD),7 whereas Doc2 contains an N-terminal Munc13-1-interacting domain (MID). C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the first C2 repeat, C2A, and has a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  26 FGQLKLSI--DAQDRVLLLHIIEGKGL--MSrEPGICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHF-FFPVPEE 100
Cdd:cd04035     1 LGTLEFTLlyDPANSALHCTIIRAKGLkaMD-ANGLSDPYVKLNLLPGASKATKLRTKTVHKTRNPEFNETLtYYGITEE 79

                          90       100       110
                  ....*....|....*....|....*....|....
gi 1720409246 101 GDQKRLL-VTVWNRasETRQHTLIGCMSFGVRSL 133
Cdd:cd04035    80 DIQRKTLrLLVLDE--DRFGNDFLGETRIPLKKL 111

C2 domain second repeat present in Synaptotagmin 15; Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. It is thought to be involved in the trafficking and exocytosis of secretory vesicles in non-neuronal tissues and is Ca2+ independent. Human synaptotagmin 15 has 2 alternatively spliced forms that encode proteins with different C-termini. The larger, SYT15a, contains a N-terminal TM region, a putative fatty-acylation site, and 2 tandem C terminal C2 domains. The smaller, SYT15b, lacks the C-terminal portion of the second C2 domain. Unlike most other synaptotagmins it is nearly absent in the brain and rather is found in the heart, lungs, skeletal muscle, and testis. Previously all synaptotagmins were thought to be calcium sensors in the regulation of neurotransmitter release and hormone secretion, but it has been shown that not all of them bind calcium. Of the 17 identified synaptotagmins only 8 bind calcium (1-3, 5-7, 9, 10). The function of the two C2 domains that bind calcium are: regulating the fusion step of synaptic vesicle exocytosis (C2A) and binding to phosphatidyl-inositol-3,4,5-triphosphate (PIP3) in the absence of calcium ions and to phosphatidylinositol bisphosphate (PIP2) in their presence (C2B). C2B also regulates also the recycling step of synaptic vesicles. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the second C2 repeat, C2B, and has a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  26 FGQLKLSI---DAQDRvLLLHIIEGKGLMSREPGICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHFFFPVPEEG- 101
Cdd:cd08409     1 LGDIQISLtynPTLNR-LTVVVLRARGLRQLDHAHTSVYVKVSLMIHNKVVKTKKTEVVDGAASPSFNESFSFKVTSRQl 79

                          90       100
                  ....*....|....*....|....*...
gi 1720409246 102 DQKRLLVTVWNrASETRQHTLIGCMSFG 129
Cdd:cd08409    80 DTASLSLSVMQ-SGGVRKSKLLGRVVLG 106

C2 domain found in Human protein Kibra; Kibra is thought to be a regulator of the Salvador (Sav)/Warts (Wts)/Hippo (Hpo) (SWH) signaling network, which limits tissue growth by inhibiting cell proliferation and promoting apoptosis. The core of the pathway consists of a MST and LATS family kinase cascade that ultimately phosphorylates and inactivates the YAP/Yorkie (Yki) transcription coactivator. The FERM domain proteins Merlin (Mer) and Expanded (Ex) are part of the upstream regulation controlling pathway mechanism. Kibra colocalizes and associates with Mer and Ex and is thought to transduce an extracellular signal via the SWH network. The apical scaffold machinery that contains Hpo, Wts, and Ex recruits Yki to the apical membrane facilitating its inhibitory phosphorlyation by Wts. Since Kibra associates with Ex and is apically located it is hypothesized that KIBRA is part of the scaffold, helps in the Hpo/Wts complex, and helps recruit Yki for inactivation that promotes SWH pathway activity. Kibra contains two amino-terminal WW domains, an internal C2-like domain, and a carboxy-terminal glutamic acid-rich stretch. The C2 domain was first identified in PKC. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  28 QLKLSIDAQDRVLLLHIIEGKGLMSRE-PGICDPYVKVSLIPEDSQLPCQ-TTQIIPDCRDPAFHEHFFFPVPEEG-DQK 104
Cdd:cd08680     4 QIGLRYDSGDSSLVISVEQLRNLSALSiPENSKVYVRVALLPCSSSTSCLfRTKALEDQDKPVFNEVFRVPISSTKlYQK 83

                          90       100
                  ....*....|....*....|.
gi 1720409246 105 RLLVTVWNRaSETRQHTLIGC 125
Cdd:cd08680    84 TLQVDVCSV-GPDQQEECLGG 103

C2 domain second repeat present in Synaptotagmins 3, 5, 6, 9, and 10; Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. Synaptotagmin 3, a member of class 3 synaptotagmins, is located in the brain and localized to the active zone and plasma membrane. It functions as a Ca2+ sensor for fast exocytosis. It, along with synaptotagmins 5,6, and 10, has disulfide bonds at its N-terminus. Synaptotagmin 9, a class 5 synaptotagmins, is located in the brain and localized to the synaptic vesicles. It is thought to be a Ca2+-sensor for dense-core vesicle exocytosis. Previously all synaptotagmins were thought to be calcium sensors in the regulation of neurotransmitter release and hormone secretion, but it has been shown that not all of them bind calcium. Of the 17 identified synaptotagmins only 8 bind calcium (1-3, 5-7, 9, 10). The function of the two C2 domains that bind calcium are: regulating the fusion step of synaptic vesicle exocytosis (C2A) and binding to phosphatidyl-inositol-3,4,5-triphosphate (PIP3) in the absence of calcium ions and to phosphatidylinositol bisphosphate (PIP2) in their presence (C2B). C2B also regulates also the recycling step of synaptic vesicles. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the second C2 repeat, C2B, and has a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  22 YLTTFGQLKLSIDAQDRVLLLHIIegkglmsrepGICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHFFFPVPEEG 101
Cdd:cd08403     9 YLPTAGRLTLTIIKARNLKAMDIT----------GFSDPYVKVSLMCEGRRLKKKKTSVKKNTLNPTYNEALVFDVPPEN 78

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1720409246 102 -DQKRLLVTV--WNRASETRqhtLIGCMSFGVRS-----------LLTPDKEISGWYYL 146
Cdd:cd08403    79 vDNVSLIIAVvdYDRVGHNE---LIGVCRVGPNAdgqgrehwnemLANPRKPIAQWHQL 134

C2 domain second repeat of Ras GTPase activating proteins (GAPs); RasGAPs suppress Ras function by enhancing the GTPase activity of Ras proteins resulting in the inactive GDP-bound form of Ras. In this way it can control cellular proliferation and differentiation. The proteins here all contain two tandem C2 domains, a Ras-GAP domain, and a pleckstrin homology (PH)-like domain. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. Members here have a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  40 LLLHIIEGKGLMSREPGICDPYVKVSLIPEDSQlPCQTTQIIPDCRDPAFHEHFFFPVP--------------EEGDQKR 105
Cdd:cd08675     1 LSVRVLECRDLALKSNGTCDPFARVTLNYSSKT-DTKRTKVKKKTNNPRFDEAFYFELTigfsyekksfkveeEDLEKSE 79

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|
gi 1720409246 106 LLVTVWNrASETRQHTLIGCMSFGVRSLLTPDKEiSGWYYLLGEDLGRTK 155
Cdd:cd08675    80 LRVELWH-ASMVSGDDFLGEVRIPLQGLQQAGSH-QAWYFLQPREAPGTR 127

circularly permuted first PDZ domain (PDZ1) of Escherichia coli periplasmic serine endoprotease DegP and related domains; PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain 1 of Escherichia coli DegP (also known as heat shock protein DegP and Protease Do) and related domains. DegP belongs to the HtrA family of housekeeping proteases. It acts as a protease, degrading transiently denatured and unfolded or misfolded proteins which accumulate in the periplasm following heat shock or other stress conditions, and as a molecular chaperone at low temperatures. DegP has two PDZ domains in addition to the protease domain; its PDZ1 domain is responsible for identifying the distinct substrate sequences that affect degradation (degron) of the substrate sequence, and its PDZ2 domain is responsible for combining with other DegP monomers to form a stable oligomer structure. PDZ domains usually bind in a sequence-specific manner to short peptide sequences located at the C-terminal of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains and as well as those with circular permutations and domain swapping of beta-strands. The canonical PDZ domain contains six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2); arranged as A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F. This DegP family PDZ domain 1 is a circularly permuted PDZ domain which places beta-strand A on the C-terminus. Another permutation exists in the PDZ superfamily which places both beta-strands A and B on the C-terminus.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1720409246 212 VDSGGPAERAGLQQLDTVLQLNERPVEHWKcvELAHEIRSCP--SEIILLVWR 262
Cdd:cd10839    32 VLPDSPAAKAGLKAGDVILSLNGKPITSSA--DLRNRVATTKpgTKVELKILR 82

C2 domain second repeat present in Synaptotagmins 14 and 16; Synaptotagmin 14 and 16 are membrane-trafficking proteins in specific tissues outside the brain. Both of these contain C-terminal tandem C2 repeats, but only Synaptotagmin 14 has an N-terminal transmembrane domain and a putative fatty-acylation site. Previously all synaptotagmins were thought to be calcium sensors in the regulation of neurotransmitter release and hormone secretion, but it has been shown that not all of them bind calcium and this is indeed the case here. Of the 17 identified synaptotagmins only 8 bind calcium (1-3, 5-7, 9, 10). The function of the two C2 domains that bind calcium are: regulating the fusion step of synaptic vesicle exocytosis (C2A) and binding to phosphatidyl-inositol-3,4,5-triphosphate (PIP3) in the absence of calcium ions and to phosphatidylinositol bisphosphate (PIP2) in their presence (C2B). C2B also regulates also the recycling step of synaptic vesicles. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the second C2 repeat, C2B, and has a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  29 LKLSIDAQDRVLLLHIIEGKGL----MSREPgicDPYVKVSLIPEDSQL--PCQTTqIIPDCRDPAFHEHFFFPVPE-EG 101
Cdd:cd08408     6 LGLEYNALTGRLSVEVIKGSNFknlaMNKAP---DTYVKLTLLNSDGQEisKSKTS-IRRGQPDPEFKETFVFQVALfQL 81

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|..
gi 1720409246 102 DQKRLLVTVWNRASETRQHtLIGCMSFGVRSllTPDKEISGW 143
Cdd:cd08408    82 SEVTLMFSVYNKRKMKRKE-MIGWFSLGLNS--SGEEEEEHW 120

circularly permuted PDZ domain 2 (PDZ-C) of Escherichia coli Regulator of sigma-E protease (RseP) and related domains; Permuted PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain of ResP (also known as Site-2 protease RseP, and YaeL) and related domains. RseP is involved in the regulation of an extracytoplasmic stress response through the cleavage of membrane-spanning anti-stress-response transcription factor (anti-sigmaE) protein RseA; it cleaves the peptide bond between the critical alanine and cysteine in the transmembrane region of RseA, releasing the cytoplasmic domain of RseA with it associated sigmaE. RseP contains two tandem-arranged periplasmic PDZ domains (PDZ-N/PDZ1 and PDZ-C/PDZ2) which act to negatively regulate protease action on intact RseA; they serve as a size-exclusion filter which prevents the access of an intact RseA into the active site of RseP. PDZ domains usually bind in sequence-specific manner to short peptide sequences located at the C-terminal of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains and as well as those with circular permutations and domain swapping of beta-strands. The canonical PDZ domain contains six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2); arranged as beta-strands A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F. This RseP family PDZ domain is a circularly permuted PDZ domain which places both beta-strands A and B at the C-terminus. Another permutation exists in the PDZ superfamily which places beta-strand A at the C-terminus.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1720409246 212 VDSGGPAERAGLQQLDTVLQLNERPVEHWKCVELAheIRSCPSE-IILLVWR--------VVPQIKPGPDG 273
Cdd:cd23083     6 VQPNSAAEKAGLQAGDRIVKVDGQPLTQWQTFVMA--VRDNPGKpLALEIERqgsplsltLIPDSKELNQG 74

PDZ domain of sorting nexin-27 (SNX27), and related domains; PDZ (PSD-95 (Postsynaptic density protein 95), Dlg (Discs large protein), and ZO-1 (Zonula occludens-1)) domain of SNX27, and related domains. SNX27 is involved in retrograde transport from endosome to plasma membrane. The PDZ domain of SNX27 links cargo identification to retromer-mediated transport. SNX27 binds to the retromer complex (vacuolar protein sorting 26(VPS26)-VPS29-VPS35), via its PDZ domain binding to VPS26. The SNX27 PDZ domain also binds to cargo including the G-protein-coupled receptors (GPCRs): beta2-adrenergic receptor (beta2AR), beta1AR, parathyroid hormone receptor (PTHR), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs), NMDA receptors, 5-hydroxytryptamine 4a receptors, frizzled receptors, and somatostatin receptor subtype 5 (SSTR5). Additional binding partners of the SNX27 PDZ domain include G protein-gated inwardly rectifying potassium (Kir3) channels, angiotensin-converting enzyme 2 (ACE2), and PTEN (phosphatase and tensin homolog deleted on chromosome 10); PTEN binding to SNX27 prevents SNX27's association with the retromer complex. SNX27 has been reported to be a host factor needed for efficient entry of an engineered SARS-CoV-2 variant, the spike protein of which contains a deletion at the S1/S2 subunit cleavage site; the PDZ domain of SNX27 binds angiotensin-converting enzyme 2 (ACE2), and may be involved in recycling ACE2 to the plasma membrane, thereby promoting viral entry. PDZ domains usually bind in a sequence-specific manner to short peptide sequences located at the C-terminal end of their partner proteins (known as PDZ binding motifs). The PDZ superfamily includes canonical PDZ domains as well as those with circular permutations and domain swapping mediated by beta-strands. This SNX27-like family domain is a canonical PDZ domain containing six beta-strands A-F and two alpha-helices (alpha-helix 1 and 2), arranged in the order: beta-strands A, B, C, alpha-helix 1, beta-strands D, E, alpha-helix 2 and beta-strand F.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246 188 ITIRRGKDGFGFTiccdspVR----------------------VQAVDSGGPAERAGLQQLDTVLQLNERPVE---HWKC 242
Cdd:cd23070     3 VTIVKSETGFGFN------VRgqvseggqlrsingelyaplqhVSAVLEGGAADKAGVRKGDRILEVNGVNVEgatHKQV 76

                          90
                  ....*....|....*...
gi 1720409246 243 VELaheIRSCPSEIILLV 260
Cdd:cd23070    77 VDL---IKSGGDELTLTV 91

C2A domain first repeat present in Synaptotagmins 4 and 11; Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. Synaptotagmins 4 and 11, class 4 synaptotagmins, are located in the brain. Their functions are unknown. They are distinguished from the other synaptotagmins by having and Asp to Ser substitution in their C2A domains. Previously all synaptotagmins were thought to be calcium sensors in the regulation of neurotransmitter release and hormone secretion, but it has been shown that not all of them bind calcium. Of the 17 identified synaptotagmins only 8 bind calcium (1-3, 5-7, 9, 10). The function of the two C2 domains that bind calcium are: regulating the fusion step of synaptic vesicle exocytosis (C2A) and binding to phosphatidyl-inositol-3,4,5-triphosphate (PIP3) in the absence of calcium ions and to phosphatidylinositol bisphosphate (PIP2) in their presence (C2B). C2B also regulates also the recycling step of synaptic vesicles. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the first C2 repeat, C2A, and has a type-I topology.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 1720409246  27 GQL--KLSIDAQDRVLLLHIIEGKGLMSREPGIC--DPYVKVSLIPEDSQLpcQTTQIIPDCRDPAFHEHF-FFPVP 98
Cdd:cd08388     3 GTLffSLRYNSEKKALLVNIIECRDLPAMDEQSGtsDPYVKLQLLPEKEHK--VKTRVLRKTRNPVYDETFtFYGIP 77

C2 domain second repeat present in Synaptotagmin-like proteins 1-4; All Slp members basically share an N-terminal Slp homology domain (SHD) and C-terminal tandem C2 domains (named the C2A domain and the C2B domain) with the SHD and C2 domains being separated by a linker sequence of various length. Slp1/JFC1 and Slp2/exophilin 4 promote granule docking to the plasma membrane. Additionally, their C2A domains are both Ca2+ independent, unlike the case in Slp3 and Slp4/granuphilin in which their C2A domains are Ca2+ dependent. It is thought that SHD (except for the Slp4-SHD) functions as a specific Rab27A/B-binding domain. In addition to Slps, rabphilin, Noc2, and Munc13-4 also function as Rab27-binding proteins. It has been demonstrated that Slp3 and Slp4/granuphilin promote dense-core vesicle exocytosis. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This cd contains the second C2 repeat, C2B, and has a type-I topology.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  39 VLLLHIIEGKGL-MSREPGICDPYVKVSLIPEDSQLPCQTTQIIPDCRDPAFHEHFFFP--VPEEGDQKRLLVTVWNRAS 115
Cdd:cd04020    28 ELHVWVKEAKNLpALKSGGTSDSFVKCYLLPDKSKKSKQKTPVVKKSVNPVWNHTFVYDgvSPEDLSQACLELTVWDHDK 107

                          90
                  ....*....|....
gi 1720409246 116 ETRQHtLIGCMSFG 129
Cdd:cd04020   108 LSSND-FLGGVRLG 120

C2 domain present in the Human neural precursor cell-expressed, developmentally down-regulated 4 (NEDD4) and NEDD4-like (NEDD4L/NEDD42); Nedd4 and Nedd4-2 are two of the nine members of the Human Nedd4 family. All vertebrates appear to have both Nedd4 and Nedd4-2 genes. They are thought to participate in the regulation of epithelial Na+ channel (ENaC) activity. They also have identical specificity for ubiquitin conjugating enzymes (E2). Nedd4 and Nedd4-2 are composed of a C2 domain, 2-4 WW domains, and a ubiquitin ligase Hect domain. Their WW domains can bind PPxY (PY) or LPSY motifs, and in vitro studies suggest that WW3 and WW4 of both proteins bind PY motifs in the key substrates, with WW3 generally exhibiting higher affinity. Most Nedd4 family members, especially Nedd4-2, also have multiple splice variants, which might play different roles in regulating their substrates. C2 domains fold into an 8-standed beta-sandwich that can adopt 2 structural arrangements: Type I and Type II, distinguished by a circular permutation involving their N- and C-terminal beta strands. Many C2 domains are Ca2+-dependent membrane-targeting modules that bind a wide variety of substances including bind phospholipids, inositol polyphosphates, and intracellular proteins. Most C2 domain proteins are either signal transduction enzymes that contain a single C2 domain, such as protein kinase C, or membrane trafficking proteins which contain at least two C2 domains, such as synaptotagmin 1. However, there are a few exceptions to this including RIM isoforms and some splice variants of piccolo/aczonin and intersectin which only have a single C2 domain. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1720409246  39 VLLLHIIEGKGLMSREP-GICDPYVKVSL--IPEDSQLPCQTTQIIPDCRDPAFHEHFFFPV-PEEgdqKRLLVTVW--N 112
Cdd:cd04033     1 ILRVKVLAGIDLAKKDIfGASDPYVKISLydPDGNGEIDSVQTKTIKKTLNPKWNEEFFFRVnPRE---HRLLFEVFdeN 77