D
IPR037765

Tricalbin, C2B domain

InterPro entry
Short nameC2B_Tricalbin
Overlapping
homologous
superfamilies
 
domain relationships

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
[1]
. The ER-plasma membrane tethering function of tricalbins mediates the formation of ER-PM contacts sites
[4]
which are thought to mediate transport glycerolipids between the two bilayers
[3]
.

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 β 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 second C2 repeat of tricalbins, C2B, and has a type-II topology
[2]
. 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
[2]
.

References

1.ER-to-plasma membrane tethering proteins regulate cell signaling and ER morphology. Manford AG, Stefan CJ, Yuan HL, Macgurn JA, Emr SD. Dev. Cell 23, 1129-40, (2012). View articlePMID: 23237950

2.The tricalbin C2 domains: lipid-binding properties of a novel, synaptotagmin-like yeast protein family. Schulz TA, Creutz CE. Biochemistry 43, 3987-95, (2004). View articlePMID: 15049706

3.The Extended-Synaptotagmins. Saheki Y, De Camilli P. Biochim. Biophys. Acta 1864, 1490-1493, (2017). View articlePMID: 28363589

4.PI(4,5)P(2)-dependent and Ca(2+)-regulated ER-PM interactions mediated by the extended synaptotagmins. Giordano F, Saheki Y, Idevall-Hagren O, Colombo SF, Pirruccello M, Milosevic I, Gracheva EO, Bagriantsev SN, Borgese N, De Camilli P. Cell 153, 1494-509, (2013). View articlePMID: 23791178

GO terms

molecular function

  • None

cellular component

  • None
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