title: Inhibitory effects of HSP70 chaperones on nascent polypeptides.
abstract: Several of the major heat shock proteins (HSPs) function normally as molecular chaperones to prevent aggregation of immature polypeptides and thereby facilitate folding and oligomerization. To determine their effect on nascent polypeptides, we added purified preparations of different isoforms of HSP70 to in vitro translation reactions primed by the 26S mRNA of Sindbis virus, which encodes an autoprotease that functions cotranslationally, or by the mRNA encoding the yeast vacuolar H+ATPase, which is formed by a novel transpeptidase activity that removes the central region of the initial polypeptide. In the presence of HSP70s both the autoprotease and transpeptidase activities were inhibited, indicating that these chaperones can interact with nascent polypeptides and, in the cases studied here, perturb their normal structures.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: C
authors.initials: C
authors.lastname: Ryan
authors.forename: T H
authors.initials: TH
authors.lastname: Stevens
authors.forename: M J
authors.initials: MJ
authors.lastname: Schlesinger
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002213:Capsid / Q000096:biosynthesis* / Q000235:genetics; D002417:Cattle; D005800:Genes, Fungal; D006360:Heat-Shock Proteins / Q000494:pharmacology*; D007700:Kinetics; D008862:Microsomes, Liver / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects*; D006180:Proton-Translocating ATPases / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D012845:Sindbis Virus / Q000235:genetics*; D014158:Transcription, Genetic; D014908:Triticum / Q000378:metabolism
chemical_list: D006360:Heat-Shock Proteins; D012333:RNA, Messenger; D006180:Proton-Translocating ATPases