title: Identification of novel protein-protein interactions at the cytosolic surface of the Sec63 complex in the yeast ER membrane.
abstract: Precursors of secretory proteins are targeted to the membrane of the endoplasmic reticulum by specific protein complexes that recognize their signal sequence. All eukaryotic cells investigated so far have been found to possess the signal recognition particle (SRP) that targets the majority of precursors to the translocation machinery. In Saccharomyces cerevisiae a number of proteins are translocated independently of SRP. These precursors rely on a different signal sequence-binding complex, which includes Sec62p, Sec63p, Sec71p and Sec72p. Identifying interactions between individual components of this tetrameric protein complex is important in the understanding of its function. We demonstrate a specific interaction between the only two essential proteins in this complex, Sec62p and Sec63p. Second, we show evidence of homodimerization of Sec72p molecules and further identify the YLR301w gene product as a novel in vivo interacting partner of Sec72p. Finally, we determine the authentic N-terminus of Sec62p and describe interacting subdomains of both Sec62p and Sec63p.
authors.affiliation: School of Biological Sciences, 2205 Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Willer
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Jermy
authors.forename: Barry P
authors.initials: BP
authors.lastname: Young
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Stirling
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D021381:Protein Transport / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D018271:Signal Recognition Particle / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D004271:DNA, Fungal; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C074215:SEC63 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D018271:Signal Recognition Particle