title: The use of calnexin and calreticulin by cellular and viral glycoproteins.
abstract: Calnexin and calreticulin are homologous lectin chaperones that assist maturation of cellular and viral glycoproteins in the mammalian endoplasmic reticulum. Calnexin and calreticulin share the same specificity for monoglucosylated protein-bound N-glycans but associate with a distinct set of newly synthesized polypeptides. We report here that most calnexin substrates do not associate with calreticulin even upon selective calnexin inactivation, while BiP associates more abundantly with nascent polypeptides under these conditions. Calreticulin associated more abundantly with orphan calnexin substrates only in infected cells and preferentially with polypeptides of viral origin, showing stronger dependence of model viral glycoproteins on endoplasmic reticulum lectins. This may explain why inactivation of the calnexin cycle affects viral replication and infectivity but not viability of mammalian cells.
authors.affiliation: Institute for Research in Biomedicine, 6500 Bellinzona, Switzerland.
authors.forename: Michel
authors.initials: M
authors.lastname: Pieren
authors.forename: Carmela
authors.initials: C
authors.lastname: Galli
authors.forename: Angela
authors.initials: A
authors.lastname: Denzel
authors.forename: Maurizio
authors.initials: M
authors.lastname: Molinari
mesh_terms: D053829:Amyloid Precursor Protein Secretases; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D037281:Calnexin / Q000235:genetics / Q000378:metabolism*; D037282:Calreticulin / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival; D010450:Endopeptidases; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D006023:Glycoproteins / Q000378:metabolism*; D051379:Mice; D011134:Polysaccharides / Q000378:metabolism; D012672:Semliki forest virus / Q000378:metabolism* / Q000502:physiology; D013379:Substrate Specificity; D014721:Vesicular stomatitis Indiana virus / Q000378:metabolism / Q000502:physiology; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D037282:Calreticulin; D006023:Glycoproteins; D011134:Polysaccharides; D014764:Viral Proteins; D037281:Calnexin; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509282:Bace1 protein, mouse