Tricalbin, C2A domain (IPR037761)

Short name: C2A_Tricalbin

Overlapping homologous superfamilies

Domain relationships

  • C2 domain (IPR000008)
    • Tricalbin, C2A domain (IPR037761)


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 [PMID: 23237950]. The ER-plasma membrane tethering function of tricalbins mediates the formation of ER-PM contacts sites [PMID: 23791178] which are thought to mediate transport glycerolipids between the two bilayers [PMID: 28363589].

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. C2 domains with a calcium binding region have negatively charged residues, primarily aspartates, that serve as ligands for calcium ions. This entry contains the first C2 repeat of tricalbins, C2A, and has a type-II topology [PMID: 15049706]. 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 [PMID: 15049706].

GO terms

Biological Process

GO:0061817 endoplasmic reticulum-plasma membrane tethering

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.