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The yeast NOP4 gene product is an essential nucleolar protein required for pre‐rRNA processing and accumulation of 60S ribosomal subunits.
Author(s) -
Sun C.,
Woolford J.L.
Publication year - 1994
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1994.tb06611.x
Subject(s) - biology , ribosomal rna , ribosomal protein , yeast , eukaryotic large ribosomal subunit , ribosome , gene , genetics , 18s ribosomal rna , gene product , gene expression , rna
The Saccharomyces cerevisiae NOP4 gene was isolated by screening a lambda gt11 yeast genomic DNA library with a monoclonal antibody against a yeast nucleolar protein. NOP4 encodes a 78 kDa protein that contains two prototypical RNA recognition motifs (RRMs) flanking an imperfect RRM lacking characteristic RNP1 and RNP2 motifs. In addition, there is a fourth incomplete RRM. NOP4 is a single copy essential gene present on chromosome XVI, between RAD1 and PEP4. To examine the function of Nop4p, we constructed a conditional null allele of NOP4 by placing this gene under the control of the glucose‐repressible GAL1 promoter. When cells are shifted from galactose‐containing medium to glucose‐containing medium, NOP4 transcription is terminated, Nop4 protein is depleted and cell growth is impaired. Nop4 protein depletion results in diminished accumulation of 60S ribosomal subunits, assignable to a defect in ribosome biogenesis arising from a lack of production of mature 25S rRNA from 27S precursor rRNA.