Journal of Biological Chemistry
Volume 275, Issue 7, 18 February 2000, Pages 4827-4833
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GENES: STRUCTURE AND REGULATION
ERO1-L, a Human Protein That Favors Disulfide Bond Formation in the Endoplasmic Reticulum*

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Oxidizing conditions must be maintained in the endoplasmic reticulum (ER) to allow the formation of disulfide bonds in secretory proteins. Here we report the cloning and characterization of a mammalian gene (ERO1-L) that shares extensive homology with the Saccharomyces cerevisiae ERO1 gene, required in yeast for oxidative protein folding. When expressed in mammalian cells, the product of the human ERO1-L gene co-localizes with ER markers and displays Endo-H-sensitive glycans. In isolated microsomes, ERO1-L behaves as a type II integral membrane protein. ERO1-L is able to complement several phenotypic traits of the yeast thermosensitive mutant ero1-1, including temperature and dithiothreitol sensitivity, and intrachain disulfide bond formation in carboxypeptidase Y. ERO1-L is no longer functional when either one of the highly conserved Cys-394 or Cys-397 is mutated. These results strongly suggest that ERO1-L is involved in oxidative ER protein folding in mammalian cells.

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*

This work was supported in part by grants from Associazione per la Ricerca sul Cancro, Consiglio Nazionale delle Ricerche Target Project on Biotechnology Grant CNR 97.01296.PF49 and Biotechnology Grant CNR 98.00393.PF31, Biotechnology and Biological Sciences Research Council Grant 34/C09198, AIRC, Telethon (E.672), and by cofin98-MURST.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AF081886 (H. sapiens), AF144695 (M. musculus), AF125280 (D. melanogaster), and AF123887(IMAGE clone 1485-o16).

§

The first two authors contributed equally to this work.

Present address: Dept. of Applied and Molecular Ecology, Waite Campus, Glen Osmond, South Australia 5064.