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

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 94; no. 18; pp. 9693 - 9698
• Main Authors: Sato, K, Sato, M, Nakano, A
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 02.09.1997; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences of the USA
• Subjects: Antibodies; APARATO GOLGI; APPAREIL DE GOLGI; Biological Sciences; CELL MEMBRANES; Cellular biology; DNA; ENDOPLASMIC RETICULUM; Endoplasmic Reticulum - metabolism; Fungal Proteins; Fungal Proteins - genetics; Fungal Proteins - metabolism; genetics; GLICOPROTEINAS; GLYCOPROTEINE; GLYCOPROTEINS; GOLGI APPARATUS; IMMUNOCYTOCHEMISTRY; IMMUNOLOGIE; IMMUNOLOGY; INMUNOLOGIA; MEMBRANAS CELULARES; MEMBRANE CELLULAIRE; Membrane Proteins; Membrane Proteins - genetics; Membrane Proteins - metabolism; Membranes; metabolism; METABOLISME DES PROTEINES; METABOLISMO PROTEICO; Overproduction; Plasmids; PROTEIN METABOLISM; PROTEIN TRANSPORT; PROTEINAS; PROTEINE; PROTEINS; Receptors; Recombinant Fusion Proteins; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; RETICULO ENDOPLASMATICO; RETICULUM ENDOPLASMIQUE; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae - ultrastructure; Saccharomyces cerevisiae Proteins; Secretion; ultrastructure; Vesicular Transport Proteins; Yeasts
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.94.18.9693

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 alpha-mating factor precursor (Mfalpha 1p). Although Sec71p and Sec63p have completely different topology from Sec12p, their Mfalpha 1p 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 Mfalpha 1-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 alpha-COP, a subunit of yeast coatomer, on the localization of these ER membrane proteins. The Mfalpha 1p fusions of Sec12p, Sec71p, and Sec63p were all more or less mislocalized in ret1-1. These observations imply that the roles of Rer1p an coatomer are much more general than thought before