Rer1p as common machinery for the endoplasmic reticulum localization of membrane proteins

AUTOR(ES)

Sato, Ken

FONTE

The National Academy of Sciences of the USA

RESUMO

Rer1p, a Golgi membrane protein, is required for the correct localization of an endoplasmic reticulum (ER) membrane protein, Sec12p, by a retrieval mechanism from the cis-Golgi to the ER. To test whether or not the role of Rer1p is common to multiple ER membrane proteins, we examined the localization of two other ER membrane proteins, Sec71p and Sec63p, in the wild-type and rer1 mutant yeast cells, using their fusions with an α-mating factor precursor (Mfα1p). Although Sec71p and Sec63p have completely different topology from Sec12p, their Mfα1p fusion proteins were also mislocalized to the trans-Golgi in the rer1 mutant. Overexpression of these fusions caused their mislocalization to the trans-Golgi even in the wild-type cells, and this mislocalization was partially suppressed by the co-overexpression of Rer1p. Either Sec71p or an artificial chimeric protein whose ER localization depends on Rer1p gave a competitive effect on the localization of the Mfα1-Sec71p fusion, which was abolished in rer1. Thus, Rer1p appears to be one of the common limiting components in the retrieval machinery for ER membrane proteins. The results also suggest that Sec71p and Sec63p depend on ER-Golgi recycling, at least partly, for ER localization. We also examined the effect of a mutation in α-COP, a subunit of yeast coatomer, on the localization of these ER membrane proteins. The Mfα1p fusions of Sec12p, Sec71p, and Sec63p were all more or less mislocalized in ret1–1. These observations imply that the roles of Rer1p and coatomer are much more general than thought before.

Documentos Relacionados

• Membrane protein retrieval from the Golgi apparatus to the endoplasmic reticulum (ER): characterization of the RER1 gene product as a component involved in ER localization of Sec12p.
• Endoplasmic Reticulum Quality Control of Unassembled Iron Transporter Depends on Rer1p-mediated Retrieval from the Golgi
• A subset of membrane-associated proteins is ubiquitinated in response to mutations in the endoplasmic reticulum degradation machinery
• Der3p/Hrd1p Is Required for Endoplasmic Reticulum-associated Degradation of Misfolded Lumenal and Integral Membrane Proteins
• Sec61p is part of the endoplasmic reticulum-associated degradation machinery