Sec24C/D-isoform-specific sorting of the preassembled ER-Golgi Q-SNARE complex.
Mol Biol Cell
; 27(17): 2697-707, 2016 09 01.
Article
em En
| MEDLINE
| ID: mdl-27413010
ABSTRACT
Secretory proteins are exported from the endoplasmic reticulum in COPII vesicles. SNARE proteins-core machinery for membrane fusion-are incorporated into COPII vesicles by direct interaction with Sec24. Here we report a novel mechanism for sorting of the ER-Golgi Q-SNAREs into COPII vesicles. Different mammalian Sec24 isoforms recruit either the R-SNARE Sec22b or the Q-SNAREs Syntaxin5, GS27, and Bet1. Syntaxin5 is the only Q-SNARE that directly interacts with Sec24C, requiring its "open" conformation. Mutation within the IxM cargo-binding site of Sec24C led to a drastic reduction in sorting of all three Q-SNAREs into COPII vesicles, implying their ER export as a preassembled complex. Analysis of immunoisolated COPII vesicles and intracellular localization of Sec24 isoforms indicate that all ER-Golgi SNAREs are present on the same vesicle. Combined with existing data, our findings yield a general concept of how Sec24 isoforms can recruit fusogenic SNARE subunits to keep them functionally apart and thus prime mammalian COPII vesicles for homotypic fusion.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Transporte Vesicular
/
Proteínas SNARE
Idioma:
En
Ano de publicação:
2016
Tipo de documento:
Article