title: Suppression of a sec63 mutation identifies a novel component of the yeast endoplasmic reticulum translocation apparatus.
abstract: Mutations in the SEC63 gene are associated with defects in protein translocation into the endoplasmic reticulum (ER) as well as in nuclear protein localization in Saccharomyces cerevisiae. To identify proteins that might interact and/or function with SEC63p, we cloned a high copy suppressor (HSS1) of the temperature-sensitive lethal phenotype of the sec63-101 mutant. HSS1 is an allele-specific sec63 suppressor that encodes an integral ER membrane glycoprotein of 206 amino acids with the N-terminus in the ER lumen and C-terminal region in the cytoplasm. Haploid strains disrupted for HSS1 are temperature-sensitive for growth and accumulate precursor forms of Kar2p and invertase. The HSS1 null allele is synthetically lethal in combination with mutations affecting ER translocation. We propose that HSS1p is important for ER translocation and interacts with previously identified components of the yeast translocation apparatus. HSS1 is identical to SEC66, which encodes a glycoprotein complexed with SEC62p and SEC63p.
authors.affiliation: Department of Molecular Biology, Princeton University, New Jersey 08544.
authors.forename: T
authors.initials: T
authors.lastname: Kurihara
authors.forename: P
authors.initials: P
authors.lastname: Silver
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D015825:Chromosomes, Fungal; D003001:Cloning, Molecular; D017931:DNA Primers; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics; D005800:Genes, Fungal; D005804:Genes, Lethal; D006026:Glycoside Hydrolases / Q000096:biosynthesis; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic; D043324:beta-Fructofuranosidase
chemical_list: D017931:DNA Primers; D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C060153:KAR2 protein, yeast; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C074215:SEC63 protein, S cerevisiae; C084842:SEC66 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase