Premium
Calmodulin and lipid binding to synaptobrevin regulates calcium‐dependent exocytosis
Author(s) -
Quetglas Stephanie,
Iborra Cecile,
Sasakawa Nobuyuki,
De Haro Luc,
Kumakura Konosuke,
Sato Kazuki,
Leveque Christian,
Seagar Michael
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdf404
Subject(s) - exocytosis , calmodulin , microbiology and biotechnology , synaptobrevin , syntaxin , biochemistry , biology , chemistry , synaptic vesicle , secretion , vesicle , membrane , enzyme
Neurotransmitter release involves the assembly of a heterotrimeric SNARE complex composed of the vesicle protein synaptobrevin (VAMP 2) and two plasma membrane partners, syntaxin 1 and SNAP‐25. Calcium influx is thought to control this process via Ca 2+ ‐binding proteins that associate with components of the SNARE complex. Ca 2+ /calmodulin or phospholipids bind in a mutually exclusive fashion to a C‐terminal domain of VAMP (VAMP 77–90 ), and residues involved were identified by plasmon resonance spectroscopy. Microinjection of wild‐type VAMP 77–90 , but not mutant peptides, inhibited catecholamine release from chromaffin cells monitored by carbon fibre amperometry. Pre‐incubation of PC12 pheochromocytoma cells with the irreversible calmodulin antagonist ophiobolin A inhibited Ca 2+ ‐dependent human growth hormone release in a permeabilized cell assay. Treatment of permeabilized cells with tetanus toxin light chain (TeNT) also suppressed secretion. In the presence of TeNT, exocytosis was restored by transfection of TeNT‐resistant (Q 76 V, F 77 W) VAMP, but additional targeted mutations in VAMP 77–90 abolished its ability to rescue release. The calmodulin‐ and phospholipid‐binding domain of VAMP 2 is thus required for Ca 2+ ‐dependent exocytosis, possibly to regulate SNARE complex assembly.