title: The nascent polypeptide-associated complex (NAC) of yeast functions in the targeting process of ribosomes to the ER membrane.
abstract: We study here the binding of ribosomes to the endoplasmic reticulum (ER) membrane and its dependence on nascent polypeptide-associated complex (NAC). For this, we use an in vitro translation system in combination with isolated microsomes. Importantly, all components in the system are derived from a single source, Saccharomyces cerevisiae. Ribosome nascent chains (RNCs) of the two naturally occurring invertase species (secreted or cytosolic) were prepared in wild-type, delta alpha NAC or delta alpha beta 1 beta 3 NAC translation lysates and tested for binding to the corresponding microsomal membranes. We provide evidence that NAC prevents binding of RNCs without a signal sequence to yeast membranes. In the absence of NAC, signal-less RNCs are able to bind to ER membranes. However, following puromycin treatment, only very few nascent chains translocate into the lumen, as detected by glycosylation.
authors.affiliation: Department of Biochemistry, Humboldt University, Berlin, Germany. brigitte.wiedmann@charite.de
authors.forename: B
authors.initials: B
authors.lastname: Wiedmann
authors.forename: S
authors.initials: S
authors.lastname: Prehn
mesh_terms: D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D003208:Concanavalin A / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism; D006031:Glycosylation; D007425:Intracellular Membranes / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D018832:Molecular Chaperones; D016296:Mutagenesis; D014176:Protein Biosynthesis; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D015398:Signal Transduction; D015534:Trans-Activators / Q000502:physiology*; D043324:beta-Fructofuranosidase
chemical_list: D018832:Molecular Chaperones; D015534:Trans-Activators; C096099:nascent-polypeptide-associated complex; D003208:Concanavalin A; D015500:Chloramphenicol O-Acetyltransferase; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase