Mutations in a highly conserved region of the Arf1p activator GEA2 block anterograde Golgi transport but not COPI recruitment to membranes.
Mol Biol Cell
; 16(8): 3786-99, 2005 Aug.
Article
em En
| MEDLINE
| ID: mdl-15930122
ABSTRACT
We have identified an important functional region of the yeast Arf1 activator Gea2p upstream of the catalytic Sec7 domain and characterized a set of temperature-sensitive (ts) mutants with amino acid substitutions in this region. These gea2-ts mutants block or slow transport of proteins traversing the secretory pathway at exit from the endoplasmic reticulum (ER) and the early Golgi, and accumulate both ER and early Golgi membranes. No defects in two types of retrograde trafficking/sorting assays were observed. We find that a substantial amount of COPI is associated with Golgi membranes in the gea2-ts mutants, even after prolonged incubation at the nonpermissive temperature. COPI in these mutants is released from Golgi membranes by brefeldin A, a drug that binds directly to Gea2p and blocks Arf1 activation. Our results demonstrate that COPI function in sorting of at least three retrograde cargo proteins within the Golgi is not perturbed in these mutants, but that forward transport is severely inhibited. Hence this region of Gea2p upstream of the Sec7 domain plays a role in anterograde transport that is independent of its role in recruiting COPI for retrograde transport, at least of a subset of Golgi-ER cargo.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Saccharomyces cerevisiae
/
Membrana Celular
/
Fator 1 de Ribosilação do ADP
/
Fatores de Troca do Nucleotídeo Guanina
/
Complexo I de Proteína do Envoltório
/
Proteínas de Saccharomyces cerevisiae
/
Complexo de Golgi
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Mol Biol Cell
Assunto da revista:
BIOLOGIA MOLECULAR
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
Estados Unidos