title: Requirements for the nuclear export of the small ribosomal subunit.
abstract: Eukaryotic ribosome biogenesis requires multiple steps of nuclear transport because ribosomes are assembled in the nucleus while protein synthesis occurs in the cytoplasm. Using an in situ RNA localization assay in the yeast Saccharomyces cerevisiae, we determined that efficient nuclear export of the small ribosomal subunit requires Yrb2, a factor involved in Crm1-mediated export. Furthermore, in cells lacking YRB2, the stability and abundance of the small ribosomal subunit is decreased in comparison with the large ribosomal subunit. To identify additional factors affecting small subunit export, we performed a large-scale screen of temperature-sensitive mutants. We isolated new alleles of several nucleoporins and Ran-GTPase regulators. Together with further analysis of existing mutants, we show that nucleoporins previously shown to be defective in ribosomal assembly are also defective in export of the small ribosomal subunit.
authors.affiliation: Department of Molecular Biology, Massachusetts General Hospital, Boston 02114, USA.
authors.forename: Terence I
authors.initials: TI
authors.lastname: Moy
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Silver
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000235:genetics*; D001681:Biological Assay / Q000379:methods; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D005057:Eukaryotic Cells / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D028884:Karyopherins / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D028861:Nuclear Pore Complex Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D000097606:Exportin 1 Protein
chemical_list: D020690:GTPase-Activating Proteins; D028884:Karyopherins; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D012335:RNA, Ribosomal; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; D020931:ran GTP-Binding Protein; D000097606:Exportin 1 Protein; C113422:YRB2 protein, S cerevisiae