title: Mrd1p is required for processing of pre-rRNA and for maintenance of steady-state levels of 40 S ribosomal subunits in yeast.
abstract: Ribosome biogenesis is a conserved process in eukaryotes that requires a large number of small nucleolar RNAs and trans-acting proteins. The Saccharomyces cerevisiae MRD1 (multiple RNA-binding domain) gene encodes a novel protein that contains five consensus RNA-binding domains. Mrd1p is essential for viability. Mrd1p partially co-localizes with the nucleolar protein Nop1p. Depletion of Mrd1p leads to a selective reduction of 18 S rRNA and 40 S ribosomal subunits. Mrd1p associates with the 35 S precursor rRNA (pre-rRNA) and U3 small nucleolar RNAs and is necessary for the initial processing at the A(0)-A(2) cleavage sites in pre-rRNA. The presence of five RNA-binding domains in Mrd1p suggests that Mrd1p may function to correctly fold pre-rRNA, a requisite for proper cleavage. Sequence comparisons suggest that Mrd1p homologues exist in all eukaryotes.
authors.affiliation: Department of Molecular Biology and Functional Genomics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Shao-Bo
authors.initials: SB
authors.lastname: Jin
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.forename: Petra
authors.initials: P
authors.lastname: Bjork
authors.forename: Karin
authors.initials: K
authors.lastname: Schmekel
authors.forename: Per O
authors.initials: PO
authors.lastname: Ljungdahl
authors.forename: Lars
authors.initials: L
authors.lastname: Wieslander
mesh_terms: D001483:Base Sequence; D004271:DNA, Fungal; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D016253:Microscopy, Immunoelectron; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology*; D012331:RNA, Fungal / Q000378:metabolism*; D012337:RNA, Ribosomal, 18S / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D012331:RNA, Fungal; D012337:RNA, Ribosomal, 18S