C2 domain second repeat contained in Rab3-interacting molecule (RIM) proteins; RIMs are believed to organize specialized sites of the plasma membrane called active zones. They also play a role in controlling neurotransmitter release, plasticity processes, as well as memory and learning. RIM contains an N-terminal zinc finger domain, a PDZ domain, and two C-terminal C2 domains (C2A, C2B). 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 and do not bind Ca2+.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1958804183 229 LGPAQLVGRQTLATPAMGDIQIGMEDKKGQLEVEVIRARSLTQKPGSKSTPAPYVKVYLLENGACIAKKKTRIARKTLDP 308
Cdd:cd04028     1 LGPGQLVGRQVLASPSMGDIQLGLYDKKGQLEVEVIRARGLVQKPGSKVLPAPYVKVYLLEGKKCIAKKKTKIARKTLDP 80

                          90       100       110       120       130       140
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1958804183 309 LYQQSLVFDESPQGKVLQVIVWGDYGRMDHKCFMGVAQILLEELDLSSMVIGWYKLFPPSSLVDPT 374
Cdd:cd04028    81 LYQQQLVFDVSPTGKTLQVIVWGDYGRMDKKVFMGVAQILLDDLDLSNLVIGWYKLFPTSSLVDPT 146

C2 domain second repeat contained in Rab3-interacting molecule (RIM) proteins; RIMs are believed to organize specialized sites of the plasma membrane called active zones. They also play a role in controlling neurotransmitter release, plasticity processes, as well as memory and learning. RIM contains an N-terminal zinc finger domain, a PDZ domain, and two C-terminal C2 domains (C2A, C2B). 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 and do not bind Ca2+.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1958804183 229 LGPAQLVGRQTLATPAMGDIQIGMEDKKGQLEVEVIRARSLTQKPGSKSTPAPYVKVYLLENGACIAKKKTRIARKTLDP 308
Cdd:cd04028     1 LGPGQLVGRQVLASPSMGDIQLGLYDKKGQLEVEVIRARGLVQKPGSKVLPAPYVKVYLLEGKKCIAKKKTKIARKTLDP 80

                          90       100       110       120       130       140
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1958804183 309 LYQQSLVFDESPQGKVLQVIVWGDYGRMDHKCFMGVAQILLEELDLSSMVIGWYKLFPPSSLVDPT 374
Cdd:cd04028    81 LYQQQLVFDVSPTGKTLQVIVWGDYGRMDKKVFMGVAQILLDDLDLSNLVIGWYKLFPTSSLVDPT 146

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        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1958804183  258 QLEVEVIRARSLtQKPGSKSTPAPYVKVYLleNGACIAKKKTRIARKTLDPLYQQSLVFD-ESPQGKVLQVIVWgDYGRM 336
Cdd:smart00239   1 TLTVKIISARNL-PPKDKGGKSDPYVKVSL--DGDPKEKKKTKVVKNTLNPVWNETFEFEvPPPELAELEIEVY-DKDRF 76

                           90       100
                   ....*....|....*....|....*
gi 1958804183  337 DHKCFMGVAQILLEELDLSSMVIGW 361
Cdd:smart00239  77 GRDDFIGQVTIPLSDLLLGGRHEKL 101

C2 domain second repeat contained in Rab3-interacting molecule (RIM) proteins; RIMs are believed to organize specialized sites of the plasma membrane called active zones. They also play a role in controlling neurotransmitter release, plasticity processes, as well as memory and learning. RIM contains an N-terminal zinc finger domain, a PDZ domain, and two C-terminal C2 domains (C2A, C2B). 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 and do not bind Ca2+.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1958804183 229 LGPAQLVGRQTLATPAMGDIQIGMEDKKGQLEVEVIRARSLTQKPGSKSTPAPYVKVYLLENGACIAKKKTRIARKTLDP 308
Cdd:cd04028     1 LGPGQLVGRQVLASPSMGDIQLGLYDKKGQLEVEVIRARGLVQKPGSKVLPAPYVKVYLLEGKKCIAKKKTKIARKTLDP 80

                          90       100       110       120       130       140
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1958804183 309 LYQQSLVFDESPQGKVLQVIVWGDYGRMDHKCFMGVAQILLEELDLSSMVIGWYKLFPPSSLVDPT 374
Cdd:cd04028    81 LYQQQLVFDVSPTGKTLQVIVWGDYGRMDKKVFMGVAQILLDDLDLSNLVIGWYKLFPTSSLVDPT 146

C2 domain second repeat present in class II phosphatidylinositol 3-kinases (PI3Ks); There are 3 classes of PI3Ks based on structure, regulation, and specificity. All classes contain a N-terminal C2 domain, a PIK domain, and a kinase catalytic domain. Unlike class I and class III, class II PI3Ks have additionally a PX domain and a C-terminal C2 domain containing a nuclear localization signal both of which bind phospholipids though in a slightly different fashion. PI3Ks (AKA phosphatidylinositol (PtdIns) 3-kinases) regulate cell processes such as cell growth, differentiation, proliferation, and motility. PI3Ks work on phosphorylation of phosphatidylinositol, phosphatidylinositide (4)P (PtdIns (4)P),2 or PtdIns(4,5)P2. Specifically they phosphorylate the D3 hydroxyl group of phosphoinositol lipids on the inositol ring. 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 1958804183 246 GDIQIGMEDKKGQLEVEVIRARSLtqKPGSKSTPAPYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVFDESP----Q 321
Cdd:cd08381     2 GQVKLSISYKNGTLFVMVMHAKNL--PLLDGSDPDPYVKTYLLPDPQKTTKRKTKVVRKTRNPTFNEMLVYDGLPvedlQ 79

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|...
gi 1958804183 322 GKVLQVIVWGDyGRMDHKCFMGVAQILLEELDLSSMVIGWYKL 364
Cdd:cd08381    80 QRVLQVSVWSH-DSLVENEFLGGVCIPLKKLDLSQETEKWYPL 121

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        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1958804183  258 QLEVEVIRARSLtQKPGSKSTPAPYVKVYLleNGACIAKKKTRIARKTLDPLYQQSLVFD-ESPQGKVLQVIVWgDYGRM 336
Cdd:smart00239   1 TLTVKIISARNL-PPKDKGGKSDPYVKVSL--DGDPKEKKKTKVVKNTLNPVWNETFEFEvPPPELAELEIEVY-DKDRF 76

                           90       100
                   ....*....|....*....|....*
gi 1958804183  337 DHKCFMGVAQILLEELDLSSMVIGW 361
Cdd:smart00239  77 GRDDFIGQVTIPLSDLLLGGRHEKL 101

C2 domain first repeat contained in Rab3-interacting molecule (RIM) proteins; RIMs are believed to organize specialized sites of the plasma membrane called active zones. They also play a role in controlling neurotransmitter release, plasticity processes, as well as memory and learning. RIM contains an N-terminal zinc finger domain, a PDZ domain, and two C-terminal C2 domains (C2A, C2B). 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 and do not bind Ca2+.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1958804183 248 IQIGMEDKKGQLEVEVIRARSLTQKPGSkSTPAPYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVFDESPQ----GK 323
Cdd:cd04031     7 IQLWYDKVTSQLIVTVLQARDLPPRDDG-SLRNPYVKVYLLPDRSEKSKRRTKTVKKTLNPEWNQTFEYSNVRRetlkER 85

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*
gi 1958804183 324 VLQVIVWgDYGRMDHKCFMGVAQIlleelDLSSMVIG----WYKL 364
Cdd:cd04031    86 TLEVTVW-DYDRDGENDFLGEVVI-----DLADALLDdephWYPL 124

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 1958804183 246 GDIQIGM--EDKKGQLEVEVIRARSLTqKPGSKSTPAPYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVFD---ESP 320
Cdd:cd00276     1 GELLLSLsyLPTAERLTVVVLKARNLP-PSDGKGLSDPYVKVSLLQGGKKLKKKKTSVKKGTLNPVFNEAFSFDvpaEQL 79

                          90       100
                  ....*....|....*....|...
gi 1958804183 321 QGKVLQVIVWgDYGRMDHKCFMG 343
Cdd:cd00276    80 EEVSLVITVV-DKDSVGRNEVIG 101

C2 domain third repeat present in uncharacterized human KIAA1228-like proteins; KIAA proteins are uncharacterized human proteins. They were compiled by the Kazusa mammalian cDNA project which identified more than 2000 human genes. They are identified by 4 digit codes that precede the KIAA designation. Many KIAA genes are still functionally uncharacterized including KIAA1228. 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 1958804183 246 GDIQIGME--DKKGQLEVEVIRARSLTQKPGSKStPAPYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVFDESP--- 320
Cdd:cd04030     3 GRIQLTIRysSQRQKLIVTVHKCRNLPPCDSSDI-PDPYVRLYLLPDKSKSTRRKTSVKKDNLNPVFDETFEFPVSLeel 81

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*
gi 1958804183 321 QGKVLQVIVWGDYGRMD-HKCFMGVAQILLEELDLSSMVIGWYKL 364
Cdd:cd04030    82 KRRTLDVAVKNSKSFLSrEKKLLGQVLIDLSDLDLSKGFTQWYDL 126

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 1958804183 257 GQLEVEVIRARSLTQKPGSkSTPAPYVKVYLLENGAciAKKKTRIARKTLDPLYQQSLVFDESPQ---GKVLQVIVWgDY 333
Cdd:cd08387    16 GILNVKLIQARNLQPRDFS-GTADPYCKVRLLPDRS--NTKQSKIHKKTLNPEFDESFVFEVPPQelpKRTLEVLLY-DF 91

                          90       100       110
                  ....*....|....*....|....*....|.
gi 1958804183 334 GRMDHKCFMGVAQILLEELDLSSMVIGWYKL 364
Cdd:cd08387    92 DQFSRDECIGVVELPLAEVDLSEKLDLWRKI 122

C2A domain first repeat present in Synaptotagmins 15 and 17; 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. Synaptotagmin 17 is located in the brain, kidney, and prostate and is thought to be a peripheral membrane protein. 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 1958804183 258 QLEVEVIRARSLTQKPGSKSTPAPYVKVYLLENGACiaKKKTRIARKTLDPLYQQSLVFDESP---QGKVLQVIVWgDYG 334
Cdd:cd08390    15 QLTVSLIKARNLPPRTKDVAHCDPFVKVCLLPDERR--SLQSKVKRKTQNPNFDETFVFQVSFkelQRRTLRLSVY-DVD 91

                          90       100       110
                  ....*....|....*....|....*....|..
gi 1958804183 335 RMDHKCFMGVAQILLEELDLSSMVIGWYKLFP 366
Cdd:cd08390    92 RFSRHCIIGHVLFPLKDLDLVKGGVVWRDLEP 123

C2 domain second repeat present in Synaptotagmin 4; Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. Synaptotagmin 4, a member of class 4 synaptotagmins, is located in the brain. It functions are unknown. It, like synaptotagmin-11, has an Asp to Ser substitution in its C2A domain. 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
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1958804183 257 GQLEVEVIRARSLtqkPGSKST-PA-PYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVFD 317
Cdd:cd08404    15 NRLTVVVLKARHL---PKMDVSgLAdPYVKVNLYYGKKRISKKKTHVKKCTLNPVFNESFVFD 74

C2A domain first repeat present in Synaptotagmin 7; Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. Synaptotagmin 7, a member of class 2 synaptotagmins, is located in presynaptic plasma membranes in neurons, dense-core vesicles in endocrine cells, and lysosomes in fibroblasts. It has been shown to play a role in regulation of Ca2+-dependent lysosomal exocytosis in fibroblasts and may also function as a vesicular Ca2+-sensor. It is distinguished from the other synaptotagmins by having over 12 splice forms. 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 1958804183 245 MGDIQIGMEDKKGQ--LEVEVIRARSLTQKPGSkSTPAPYVKVYLLENGAciAKKKTRIARKTLDPLYQQSLVFDESPQG 322
Cdd:cd08386     2 LGRIQFSVSYDFQEstLTLKILKAVELPAKDFS-GTSDPFVKIYLLPDKK--HKLETKVKRKNLNPHWNETFLFEGFPYE 78

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|
gi 1958804183 323 KV------LQVIvwgDYGRMDHKCFMGVAQILLEELDLSSMVIGWYKLFP 366
Cdd:cd08386    79 KLqqrvlyLQVL---DYDRFSRNDPIGEVSLPLNKVDLTEEQTFWKDLKP 125

C2 domain second repeat present in Synaptotagmin 12; Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. Synaptotagmin 12, a member of class 6 synaptotagmins, is located in the brain. It functions are unknown. It, like synaptotagmins 8 and 13, do not have any consensus Ca2+ binding sites. 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
                  ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1958804183 258 QLEVEVIRARSLTQkPGSKSTPAPYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVFDESP 320
Cdd:cd08406    16 RLTVVVVKARNLVW-DNGKTTADPFVKVYLLQDGRKISKKKTSVKRDDTNPIFNEAMIFSVPA 77

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        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1958804183 248 IQIGME--DKKGQLEVEVIRARSLTQKPGSKSTpAPYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVFDESPQ---G 322
Cdd:cd08384     2 ILVSLMynTQRRGLIVGIIRCVNLAAMDANGYS-DPFVKLYLKPDAGKKSKHKTQVKKKTLNPEFNEEFFYDIKHSdlaK 80

                          90
                  ....*....|....*.
gi 1958804183 323 KVLQVIVWG-DYGRMD 337
Cdd:cd08384    81 KTLEITVWDkDIGKSN 96

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 1958804183 258 QLEVEVIRARSLtQKPGSKSTPAPYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVF----DESPQGKVLQVIVWgDY 333
Cdd:cd04035    16 ALHCTIIRAKGL-KAMDANGLSDPYVKLNLLPGASKATKLRTKTVHKTRNPEFNETLTYygitEEDIQRKTLRLLVL-DE 93

                          90
                  ....*....|....*....
gi 1958804183 334 GRMDHKcFMGVAQILLEEL 352
Cdd:cd04035    94 DRFGND-FLGETRIPLKKL 111

C2 domain second repeat present in Synaptotagmin 17; Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. Synaptotagmin 17 is located in the brain, kidney, and prostate and is thought to be a peripheral membrane protein. 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
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1958804183 257 GQLEVEVIRARSLTQKPGSKSTPaPYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVF---DESPQGKVLQVIVWG 331
Cdd:cd08410    14 GRLNVDIIRAKQLLQTDMSQGSD-PFVKIQLVHGLKLIKTKKTSCMRGTIDPFYNESFSFkvpQEELENVSLVFTVYG 90

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 1958804183 258 QLEVEVIRARSLtQKPGSKSTPAPYVKVYLL--ENGACIAKKKTRIARKTLDPLYQQSLVFDESPQ-----GKVLQVIVw 330
Cdd:cd04009    17 SLRVEILNARNL-LPLDSNGSSDPFVKVELLprHLFPDVPTPKTQVKKKTLFPLFDESFEFNVPPEqcsveGALLLFTV- 94

                  ....*...
gi 1958804183 331 gdygrMDH 338
Cdd:cd04009    95 -----KDY 97

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        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1958804183 259 LEVEVIRARSLTQKPGSKSTpAPYVKVYLLENgaciaKKKTRIARKTLDPLYQQSLVFD----ESPQGKVLQVIVWGDYG 334
Cdd:cd04022     2 LVVEVVDAQDLMPKDGQGSS-SAYVELDFDGQ-----KKRTRTKPKDLNPVWNEKLVFNvsdpSRLSNLVLEVYVYNDRR 75

                          90
                  ....*....|....
gi 1958804183 335 RMDHKCFMGVAQIL 348
Cdd:cd04022    76 SGRRRSFLGRVRIS 89

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
                  ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 1958804183 257 GQLEVEVIRARSLTQKPGSKStPAPYVKVYLLE-NGACIAKKKTRIARKTLDPLYQQSLVF 316
Cdd:cd08408    15 GRLSVEVIKGSNFKNLAMNKA-PDTYVKLTLLNsDGQEISKSKTSIRRGQPDPEFKETFVF 74

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

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1958804183 278 TPAPYVKVYLleNGACIakKKTRIARKTLDPLYQQS---LVFDESpqGKVLQVIVWGDygRMDHKCFMGVAQILLEEL-D 353
Cdd:cd04052    12 LLSPYAELYL--NGKLV--YTTRVKKKTNNPSWNAStefLVTDRR--KSRVTVVVKDD--RDRHDPVLGSVSISLNDLiD 83

                          90
                  ....*....|.
gi 1958804183 354 LSSMVIGWYKL 364
Cdd:cd04052    84 ATSVGQQWFPL 94

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        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1958804183 258 QLEVEVIRARSLtqkPGSKSTPapYVKVYLLENgaciaKKKTRIARKTLDPLYQQSLVFD--ESPQ 321
Cdd:cd04011     5 QVRVRVIEARQL---VGGNIDP--VVKVEVGGQ-----KKYTSVKKGTNCPFYNEYFFFNfhESPD 60

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 1958804183 259 LEVEVIRARSLTQKPGSKSTPapYVKVYLLENGACIAKKkTRIARKTLDPLYQQSLVFDE----SPQGK----------- 323
Cdd:cd08675     1 LSVRVLECRDLALKSNGTCDP--FARVTLNYSSKTDTKR-TKVKKKTNNPRFDEAFYFELtigfSYEKKsfkveeedlek 77

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....
gi 1958804183 324 -VLQVIVWGDyGRMDHKCFMGVAQILLEELDLSSMVIGWYKLFP 366
Cdd:cd08675    78 sELRVELWHA-SMVSGDDFLGEVRIPLQGLQQAGSHQAWYFLQP 120

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
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 1958804183 246 GDIQIGM--EDKKGQLEVEVIRARSLtQKPGSKSTpAPYVKVYLLENGACIAKKKTRIARKTLDPLYQQSLVF 316
Cdd:cd08409     2 GDIQISLtyNPTLNRLTVVVLRARGL-RQLDHAHT-SVYVKVSLMIHNKVVKTKKTEVVDGAASPSFNESFSF 72