Conserved Protein Domain Family

cd08677: C2A_Synaptotagmin-13 
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C2 domain
Synaptotagmin is a membrane-trafficking protein characterized by a N-terminal transmembrane region, a linker, and 2 C-terminal C2 domains. Synaptotagmin 13, a member of class 6 synaptotagmins, is located in the brain. It functions are unknown. It, like synaptotagmins 8 and 12, does 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 first C2 repeat, C2A, and has a type-I topology.
PSSM-Id: 176059
View PSSM: cd08677
Aligned: 3 rows
Threshold Bit Score: 188.581
Threshold Setting Gi: 159163302
Created: 23-Mar-2010
Updated: 2-Oct-2020
Aligned Rows:
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Sequence Alignment
Format: Row Display: Color Bits: Type Selection:
1WFM_A        13 PKLHYCLDydcqkaeLFVTRLEAvtsn----hdggCDCYVQGSVanrtgsvEAQTALKKrqlHTTWEEGLVLPlaeee-- 86  human
NP_001017652 151 PKLHFSISlhkesgeLHINIVEAenis----veagCEGYISGCVsvseeqkHAHTAVHKlavHVQWGEELVFAlpmegte 226 zebrafish
XP_421100    159 PELRYSLTydqqkaeLCVALLEAmhgkmssdqdtgCHCYILGTLvsksgmtEAQTELKKkvlHTLWEEALRFPlteee-- 236 chicken
1WFM_A        87 ---lptaTLTLTLRTCDrfsrhsVAGELRLgldgtsvplgaAQWGEL 130 human
NP_001017652 227 dtdsldgEVALSLHCCDrfshnsTLGMMRFkladvsmmldaDCWVDL 273 zebrafish
XP_421100    237 ---mqegTLTLTLRNCDkfsrhsIVGELKLslanm-edfgmAQWERL 279 chicken
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