Calmodulin and lipid binding to synaptobrevin regulates calcium-dependent exocytosis.
EMBO J
; 21(15): 3970-9, 2002 Aug 01.
Article
em En
| MEDLINE
| ID: mdl-12145198
ABSTRACT
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.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Fosfolipídeos
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Calmodulina
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Catecolaminas
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Células Cromafins
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Proteínas de Transporte Vesicular
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Exocitose
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Proteínas de Membrana
Idioma:
En
Ano de publicação:
2002
Tipo de documento:
Article