title: NOP3 is an essential yeast protein which is required for pre-rRNA processing.
abstract: The four nucleolar proteins NOP1, SSB1, GAR1, and NSR1 of Saccharomyces cerevisiae share a repetitive domain composed of repeat units rich in glycine and arginine (GAR domain). We have cloned and sequenced a fifth member of this family, NOP3, and shown it to be essential for cell viability. The NOP3 open reading frame encodes a 415 amino acid protein with a predicted molecular mass of 45 kD, containing a GAR domain and an RNA recognition motif. NOP3-specific antibodies recognize a 60-kD protein by SDS-PAGE and decorate the nucleolus and the surrounding nucleoplasm. A conditional lethal mutation, GAL::nop3, was constructed; growth of the mutant strain in glucose medium represses NOP3 expression. In cells depleted of NOP3, production of cytoplasmic ribosomes is impaired. Northern analysis and pulse-chase labeling indicate that pre-rRNA processing is inhibited at the late steps, in which 27SB pre-rRNA is cleaved to 25S rRNA and 20S pre-rRNA to 18S rRNA.
authors.affiliation: European Molecular Biology Laboratory, Heidelberg, Germany.
authors.forename: I D
authors.initials: ID
authors.lastname: Russell
authors.forename: D
authors.initials: D
authors.lastname: Tollervey
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002466:Cell Nucleolus / Q000737:chemistry; D002467:Cell Nucleus / Q000737:chemistry; D003001:Cloning, Molecular; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012331:RNA, Fungal / Q000378:metabolism; D016601:RNA-Binding Proteins; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D005656:Fungal Proteins; C077734:NPL3 protein, S cerevisiae; D009687:Nuclear Proteins; D012322:RNA Precursors; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins