Distinct roles of the C2A and the C2B domain of the vesicular Ca2+ sensor synaptotagmin 9 in endocrine beta-cells.

ABSTRACT: Synaptotagmins form a family of calcium-sensor proteins implicated in exocytosis, and these vesicular transmembrane proteins are endowed with two cytosolic calcium-binding C2 domains, C2A and C2B. Whereas the isoforms syt1 and syt2 have been studied in detail, less is known about syt9, the calcium sensor involved in endocrine secretion such as insulin release from large dense core vesicles in pancreatic beta-cells. Using cell-based assays to closely mimic physiological conditions, we observed SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor)-independent translocation of syt9C2AB to the plasma membrane at calcium levels corresponding to endocrine exocytosis, followed by internalization to endosomes. The use of point mutants and truncations revealed that i

SUBMITTER: Grise F 

PROVIDER: S-EPMC1876385 | biostudies-literature | 2007 May

REPOSITORIES: biostudies-literature