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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 459666820   1 FGNKEVEKIDAYVSIDVDENHLGVSTTKPKTFDPVWNENFSHEVHNAKNLSLTVFHDAAIPPDDFVANCNIPFEDMMQR 79
Cdd:cd04014   27 VPKKGSQLLDPYVSIDVDDTHIGKTSTKPKTNSPVWNEEFTTEVHNGRNLELTVFHDAAIGPDDFVANCTISFEDLIQR 105

C2 domain in Protein Kinase C (PKC) epsilon; A single C2 domain is found in PKC epsilon. 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-II topology.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 459666820   1 FGNKEVEKIDAYVSIDVDENHLGVSTTKPKTFDPVWNENFSHEVHNAKNLSLTVFHDAAIPPDDFVANCNIPFEDMMQR 79
Cdd:cd04014   27 VPKKGSQLLDPYVSIDVDDTHIGKTSTKPKTNSPVWNEEFTTEVHNGRNLELTVFHDAAIGPDDFVANCTISFEDLIQR 105

Protein kinase C conserved region 2 (CalB); Ca2+-binding motif present in phospholipases, protein kinases C, and synaptotagmins (among others). Some do not appear to contain Ca2+-binding sites. Particular C2s appear to bind phospholipids, inositol polyphosphates, and intracellular proteins. Unusual occurrence in perforin. Synaptotagmin and PLC C2s are permuted in sequence with respect to N- and C-terminal beta strands. SMART detects C2 domains using one or both of two profiles.

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 459666820     8 KIDAYV--SIDVDENHLGVSTTKPKTFDPVWNENFSHEVHNAKN--LSLTVFHDAAIPPDDFVANCNIPFEDMMQR 79
Cdd:smart00239  20 KSDPYVkvSLDGDPKEKKKTKVVKNTLNPVWNETFEFEVPPPELaeLEIEVYDKDRFGRDDFIGQVTIPLSDLLLG 95

C2 domain in Protein Kinase C (PKC) epsilon; A single C2 domain is found in PKC epsilon. 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-II topology.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 459666820   1 FGNKEVEKIDAYVSIDVDENHLGVSTTKPKTFDPVWNENFSHEVHNAKNLSLTVFHDAAIPPDDFVANCNIPFEDMMQR 79
Cdd:cd04014   27 VPKKGSQLLDPYVSIDVDDTHIGKTSTKPKTNSPVWNEEFTTEVHNGRNLELTVFHDAAIGPDDFVANCTISFEDLIQR 105

Protein kinase C conserved region 2 (CalB); Ca2+-binding motif present in phospholipases, protein kinases C, and synaptotagmins (among others). Some do not appear to contain Ca2+-binding sites. Particular C2s appear to bind phospholipids, inositol polyphosphates, and intracellular proteins. Unusual occurrence in perforin. Synaptotagmin and PLC C2s are permuted in sequence with respect to N- and C-terminal beta strands. SMART detects C2 domains using one or both of two profiles.

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 459666820     8 KIDAYV--SIDVDENHLGVSTTKPKTFDPVWNENFSHEVHNAKN--LSLTVFHDAAIPPDDFVANCNIPFEDMMQR 79
Cdd:smart00239  20 KSDPYVkvSLDGDPKEKKKTKVVKNTLNPVWNETFEFEVPPPELaeLEIEVYDKDRFGRDDFIGQVTIPLSDLLLG 95

C2 domain found in Rab11-family interacting proteins (FIP) class I; Rab GTPases recruit various effector proteins to organelles and vesicles. Rab11-family interacting proteins (FIPs) are involved in mediating the role of Rab11. FIPs can be divided into three classes: class I FIPs (Rip11a, Rip11b, RCP, and FIP2) which contain a C2 domain after N-terminus of the protein, class II FIPs (FIP3 and FIP4) which contain two EF-hands and a proline rich region, and class III FIPs (FIP1) which exhibits no homology to known protein domains. All FIP proteins contain a highly conserved, 20-amino acid motif at the C-terminus of the protein, known as Rab11/25 binding domain (RBD). Class I FIPs are thought to bind to endocytic membranes via their C2 domain, which interacts directly with phospholipids. Class II FIPs do not have any membrane binding domains leaving much to speculate about the mechanism involving FIP3 and FIP4 interactions with endocytic membranes. The members in this CD are class I FIPs. The exact function of the Rab11 and FIP interaction is unknown, but there is speculation that it involves the role of forming a targeting complex that recruits a group of proteins involved in membrane transport to organelles. 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 459666820  10 DAYVSIDVDENHLGVSTTKpKTFDPVWNE-------NFSHEVHNAKNLSLTVFHDAAIPPDDFVANCNIPFEDM 76
Cdd:cd08682   21 DAYVIIQLGKEKYSTSVKE-KTTSPVWKEecsfelpGLLSGNGNRATLQLTVMHRNLLGLDKFLGQVSIPLNDL 93

C2 domain first 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 second C2 repeat, C2B, and has a type-II topology.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*
gi 459666820  24 VSTTKPKTFDPVWNENFSHEVHNAKNLSLTVF---HDaaippDDFVANCNIPFED 75
Cdd:cd08676   92 VTEVKPQTLNPVWNETFRFEVEDVSNDQLHLDiwdHD-----DDFLGCVNIPLKD 141

C2 domain first repeat found in Multiple C2 domain and Transmembrane region Proteins (MCTP); plant subset; MCTPs are involved in Ca2+ signaling at the membrane. Plant-MCTPs are composed of a variable N-terminal sequence, four C2 domains, two transmembrane regions (TMRs), and a short C-terminal sequence. It is one of four protein classes that are anchored to membranes via a transmembrane region; the others being synaptotagmins, extended synaptotagmins, and ferlins. MCTPs are the only membrane-bound C2 domain proteins that contain two functional TMRs. MCTPs are unique in that they bind Ca2+ but not phospholipids. 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-II topology.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|..
gi 459666820  11 AYVSIDVDeNHLGVSTTKPKTFDPVWNENFSHEVHNAKNLS-----LTVFHD 57
Cdd:cd04022   23 AYVELDFD-GQKKRTRTKPKDLNPVWNEKLVFNVSDPSRLSnlvleVYVYND 73

C2 domain first and third repeat in Synaptotagmin-like proteins; 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 either the first or third repeat in Synaptotagmin-like proteins with a type-I topology.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 459666820   8 KIDAYVSIDVDENHLGVSTTKpKTFDPVWNENFSHEVHNAKNLSLTV-FHDAAIPPDDFVANCNIPFED 75
Cdd:cd08391   27 KSDPYVIVRVGAQTFKSKVIK-ENLNPKWNEVYEAVVDEVPGQELEIeLFDEDPDKDDFLGRLSIDLGS 94

C2 domain second 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 second C2 repeat, C2B, and has a type-I topology.

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 459666820  10 DAYVSI----DVDENHLGVSTTKPKTFDPVWNENFSHEV-HN---AKNLSLTVF-HDAAiPPDDFVANC 69
Cdd:cd08384   35 DPFVKLylkpDAGKKSKHKTQVKKKTLNPEFNEEFFYDIkHSdlaKKTLEITVWdKDIG-KSNDYIGGL 102

C2 domain third repeat present in Tricalbin-like proteins; 5 to 6 copies of the C2 domain are present in Tricalbin, a yeast homolog of Synaptotagmin, which is involved in membrane trafficking and sorting. 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 459666820   3 NKE-VEKIDAYVSIDVDENHLGVSTTKPKTFDPVWNENFSHEVHNAK-NLSLTVFHDAAIPPDDFVANCNIPFEDMMQR 79
Cdd:cd04045   15 NLEgVGKIDPYVRVLVNGIVKGRTVTISNTLNPVWDEVLYVPVTSPNqKITLEVMDYEKVGKDRSLGSVEINVSDLIKK 93

C2 domain second repeat in Munc13 (mammalian uncoordinated) 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 second C2 repeat, C2B, and has a type-II topology.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|
gi 459666820  10 DAYVSIDVDENHLGVSTTkPKTFDPVWNENFSHEVHNAKN 49
Cdd:cd04027   23 DPYVTVQVGKTKKRTKTI-PQNLNPVWNEKFHFECHNSSD 61

C2 domain present in Smad ubiquitination-related factor (Smurf)-like proteins; A single C2 domain is found in Smurf proteins, C2-WW-HECT-domain E3s, which play an important role in the downregulation of the TGF-beta signaling pathway. Smurf proteins also regulate cell shape, motility, and polarity by degrading small guanosine triphosphatases (GTPases). 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 type-II topology.

                         10        20        30        40
                 ....*....|....*....|....*....|....*....|....*.
gi 459666820  10 DAYVSIDVDENHLGVSTTKPKTFDPVWNENFSHEVHNAKNLSLTVF 55
Cdd:cd08382   22 DPFAVITVDGGQTHSTDVAKKTLDPKWNEHFDLTVGPSSIITIQVF 67

C2 domain found in the Human chromosome 21 open reading frame 25 (C21orf25) protein; The members in this cd are named after the Human C21orf25 which contains a single C2 domain. Several other members contain a C1 domain downstream of the C2 domain. No other information on this protein is currently known. 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
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 459666820   9 IDAYVSIDVDE---NHlgVSTTKPKTFDPVWNENFSHEVHNA-KNLSLTVFHDAAIPPDDFVANCNIPFEDMMQ 78
Cdd:cd08678   18 SNPYCVLEMDEppqKY--QSSTQKNTSNPFWDEHFLFELSPNsKELLFEVYDNGKKSDSKFLGLAIVPFDELRK 89

C2 domain second repeat in Ferlin; Ferlins are involved in vesicle fusion events. Ferlins and other proteins, such as Synaptotagmins, are implicated in facilitating the fusion process when cell membranes fuse together. There are six known human Ferlins: Dysferlin (Fer1L1), Otoferlin (Fer1L2), Myoferlin (Fer1L3), Fer1L4, Fer1L5, and Fer1L6. Defects in these genes can lead to a wide range of diseases including muscular dystrophy (dysferlin), deafness (otoferlin), and infertility (fer-1, fertilization factor-1). Structurally they have 6 tandem C2 domains, designated as (C2A-C2F) and a single C-terminal transmembrane domain, though there is a new study that disputes this and claims that there are actually 7 tandem C2 domains with another C2 domain inserted between C2D and C2E. In a subset of them (Dysferlin, Myoferlin, and Fer1) there is an additional conserved domain called DysF. 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-II topology.

                         10        20        30        40        50
                 ....*....|....*....|....*....|....*....|....*....|....*
gi 459666820   9 IDAYVSIDV-DENHlgVSTTKPKTFDPVWNENFSHEVHNAKN------LSLTVFH 56
Cdd:cd04011   21 IDPVVKVEVgGQKK--YTSVKKGTNCPFYNEYFFFNFHESPDelfdkiIKISVYD 73