title: Nop9 is an RNA binding protein present in pre-40S ribosomes and required for 18S rRNA synthesis in yeast.
abstract: Proteomic analyses in yeast have identified a large number of proteins that are associated with preribosomal particles. However, the product of the yeast ORF YJL010C, herein designated as Nop9, failed to be identified in any previous physical or genetic analysis of preribosomes. Here we report that Nop9 is a nucleolar protein, which is associated with 90S and 40S preribosomes. In cells depleted of Nop9p, early cleavages of the 35S pre-rRNA are inhibited, resulting in the nucleolar retention of accumulated precursors and a failure to synthesize 18S rRNA. Nop9 contains multiple pumilio-like putative RNA binding repeats and displays robust in vitro RNA binding activity. The identification of Nop9p as a novel, essential factor in the nuclear maturation of 90S and pre-40S ribosomal subunits shows that the complement of ribosome synthesis factors remains incomplete.
authors.affiliation: Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland.
authors.forename: Emma
authors.initials: E
authors.lastname: Thomson
authors.forename: Juri
authors.initials: J
authors.lastname: Rappsilber
authors.forename: David
authors.initials: D
authors.lastname: Tollervey
mesh_terms: D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D016366:Open Reading Frames; D012331:RNA, Fungal / Q000378:metabolism*; D012337:RNA, Ribosomal, 18S / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C525831:Nop9 protein, S cerevisiae; D009687:Nuclear Proteins; D012331:RNA, Fungal; D012337:RNA, Ribosomal, 18S; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins