Agonist-activated Ca2+ influx occurs at stable plasma membrane and endoplasmic reticulum junctions.

ABSTRACT: Junctate is a 33 kDa integral protein of sarco(endo)plasmic reticulum membranes that forms a macromolecular complex with inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] receptors and TRPC3 channels. TIRF microscopy shows that junctate enhances the number of fluorescent puncta on the plasma membrane. The size and distribution of these puncta are not affected by the addition of agonists that mobilize Ca(2+) from Ins(1,4,5)P(3)-sensitive stores. Puncta are associated with a significantly larger number of peripheral junctions between endoplasmic reticulum and plasma membrane, which are further enhanced upon stable co-expression of junctate and TRPC3. The gap between the membranes of peripheral junctions is bridged by regularly spaced electron-dense structures of 10 nm. Ins(1,4,5)P(3) inhibits th

SUBMITTER: Treves S 

PROVIDER: S-EPMC2987444 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature