title: Yos9 protein is essential for degradation of misfolded glycoproteins and may function as lectin in ERAD.
abstract: The Htm1/EDEM protein has been proposed to act as a "degradation lectin" for endoplasmic reticulum-associated degradation (ERAD) of misfolded glycoproteins. In this study, we provide genetic and biochemical evidence that Yos9 protein in Saccharomyces cerevisiae is essential for efficient degradation of mutant glycoproteins. Yos9 is a member of the OS-9 protein family, which is conserved among eukaryotes and shows similarities with mannose-6-phosphate receptors (MPRs). We found that amino acids conserved among OS-9 family members and MPRs were essential for Yos9 protein function. Immunoprecipitation showed that Yos9 specifically associated with misfolded carboxypeptidase Y (CPY*), an ERAD substrate, but only when it carried Man8GlcNAc2 or Man5GlcNAc2 N-glycans. Our experiments further suggested that Yos9 acts in the same pathway as Htm1/EDEM. Yos9 protein is important for glycoprotein degradation and may act via its MRH domain as a degradation lectin-like protein in the glycoprotein degradation pathway.
authors.affiliation: Institute of Microbiology, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland.
authors.forename: Reka
authors.initials: R
authors.lastname: Szathmary
authors.forename: Regula
authors.initials: R
authors.lastname: Bielmann
authors.forename: Mihai
authors.initials: M
authors.lastname: Nita-Lazar
authors.forename: Patricie
authors.initials: P
authors.lastname: Burda
authors.forename: Claude A
authors.initials: CA
authors.lastname: Jakob
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002268:Carboxypeptidases / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D043402:Cathepsin A; D006023:Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D037102:Lectins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D002352:Carrier Proteins; D006023:Glycoproteins; D037102:Lectins; D011134:Polysaccharides; D029701:Saccharomyces cerevisiae Proteins; C495027:Yos9 protein, S cerevisiae; D002268:Carboxypeptidases; D043402:Cathepsin A; C499283:PRC1 protein, S cerevisiae