| Primary Identifier | IPR037756 | Type | Domain |
| Short Name | C2D_Tricalbin |
| description | Tricalbins (Tcb1/2/3) are yeast orthologues of the extended synaptotagmins. Tricalbins contain a transmembrane domain in their N-termini and lipid-binding C2 domains in their long cytoplasmic carboxyl-termini. As extended synaptotagmins, tricalbins also possess a synaptotagmin-like mitochondrial lipid-binding protein (SMP) domain that is found in proteins localized to ER-organelle contact sites []. The ER-plasma membrane tethering function of tricalbins mediates the formation of ER-PM contacts sites []which are thought to mediate transport glycerolipids between the two bilayers [].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 contains the fourth C2 repeat of tricalbins, C2D, and has a type-II topology []. The C2 domains of tricalbins 1 and 3 are calcium-dependent lipid-binding units comparable to mammalian synaptotagmin C2 domains, while tricalbin 2 does not seem to bind lipids in response to calcium signaling []. |
