Crystal structure of Sar1-GDP at 1.7 A resolution and the role of the NH2 terminus in ER export.
J Cell Biol
; 155(6): 937-48, 2001 Dec 10.
Article
em En
| MEDLINE
| ID: mdl-11739406
ABSTRACT
The Sar1 GTPase is an essential component of COPII vesicle coats involved in export of cargo from the ER. We report the 1.7-A structure of Sar1 and find that consistent with the sequence divergence of Sar1 from Arf family GTPases, Sar1 is structurally distinct. In particular, we show that the Sar1 NH2 terminus contains two regions an NH2-terminal extension containing an evolutionary conserved hydrophobic motif that facilitates membrane recruitment and activation by the mammalian Sec12 guanine nucleotide exchange factor, and an alpha1' amphipathic helix that contributes to interaction with the Sec23/24 complex that is responsible for cargo selection during ER export. We propose that the hydrophobic Sar1 NH2-terminal activation/recruitment motif, in conjunction with the alpha1' helix, mediates the initial steps in COPII coat assembly for export from the ER.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Monoméricas de Ligação ao GTP
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Proteínas de Saccharomyces cerevisiae
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Retículo Endoplasmático
/
Guanosina Difosfato
Limite:
Animals
Idioma:
En
Revista:
J Cell Biol
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Estados Unidos