Munc13-4 functions as a Ca²⁺ sensor for homotypic secretory granule fusion to generate endosomal exocytic vacuoles.

ABSTRACT: Munc13-4 is a Ca²⁺-dependent SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor)- and phospholipid-binding protein that localizes to and primes secretory granules (SGs) for Ca²⁺-evoked secretion in various secretory cells. Studies in mast cell-like RBL-2H3 cells provide direct evidence that Munc13-4 with its two Ca²⁺-binding C2 domains functions as a Ca²⁺ sensor for SG exocytosis. Unexpectedly, Ca²⁺ stimulation also generated large (>2.4 μm in diameter) Munc13-4⁺/Rab7⁺/Rab11⁺ endosomal vacuoles. Vacuole generation involved the homotypic fusion of Munc13-4⁺/Rab7⁺ SGs, followed by a merge with Rab11⁺ endosomes, and depended on Ca²⁺

SUBMITTER: Woo SS 

PROVIDER: S-EPMC5349786 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature