| Primary Identifier | IPR037752 | Type | Domain |
| Short Name | C2C_KIAA1228 |
| description | The extended-synaptotagmins derive their name from their partial domain structure similarity to the synaptotagmins, characterised by an N-terminal membrane anchor and cytosolically exposed C2 domains. Additionally they contain an SMP (synaptotagmin-like mitochondrial-lipid-binding protein) domain and multiple C2 domains (five in E-Syt1 and three in E-Syt2 and E-Syt3). However, the function of extended-synaptotagmins is different to that of synaptotagmins, which are involved in secretory vesicle tethering to the plasma membrane and exocytosis. The extended-synaptotagmins are located to the endoplasmic reticulum (ER), and tether this organelle to the plasma membrane via their C2 domains. They transport glycerolipids between the two bilayers via their lipid-harboring SMP domains. Ca2+ regulates their membrane tethering and lipid transport function [, , ].C2 domains fold into an 8-standed β-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. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This entry represents the C-terminal C2 domain in extendend synaptotagmins, which have a type-I topology []. |
