title: Membrane topology of the endoplasmic reticulum to Golgi transport factor Erv29p.
abstract: Secretory proteins are transported from the endoplasmic reticulum to the Golgi apparatus via COPII-coated intermediates. Yeast Erv29p is a transmembrane protein cycling between these compartments. It is conserved across species, with one ortholog found in each genome studied, including the surf-4 protein in mammals. Yeast Erv29p acts as a receptor, loading a specific subset of soluble cargo, including glycosylated alpha factor pheromone precursor and carboxypeptidase Y, into vesicles. As the eukaryotic secretory pathway is highly conserved, mammalian surf-4 may perform a similar role in the transport of unknown substrates. Here we report the membrane topology of yeast Erv29p, which we solved by minimally invasive cysteine accessibility scanning using thiol-specific biotinylation and fluorescent labeling methods. Erv29p contains four transmembrane domains with both termini exposed to the cytosol. Two luminal loops may contain a recognition site for hydrophobic export signals on soluble cargo.
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Illinois, USA.
authors.forename: Deirdre A
authors.initials: DA
authors.lastname: Foley
authors.forename: Hayley J
authors.initials: HJ
authors.lastname: Sharpe
authors.forename: Stefan
authors.initials: S
authors.lastname: Otte
mesh_terms: D000818:Animals; D001665:Binding Sites; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007425:Intracellular Membranes / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry*; D015336:Molecular Probe Techniques; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D033921:Vesicular Transport Proteins
chemical_list: C432391:Erv29 protein, S cerevisiae; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins