Abstract
We report the characterization of a novel factor, Nob1p (Yor056c), which is essential for the synthesis of 40S ribosome subunits. Genetic depletion of Nob1p strongly inhibits the processing of the 20S pre-rRNA to the mature 18S rRNA, leading to the accumulation of high levels of the 20S pre-rRNA together with novel degradation intermediates. 20S processing occurs within a pre-40S particle after its export from the nucleus to the cytoplasm. Consistent with a direct role in this cleavage, Nob1p was shown to be associated with the pre-40S particle and to be present in both the nucleus and the cytoplasm. This suggests that Nob1p accompanies the pre-40S ribosomes during nuclear export. Pre-40S export is not, however, inhibited by depletion of Nob1p.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Active Transport, Cell Nucleus
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Alleles
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Amino Acid Motifs
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Amino Acid Sequence
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Blotting, Northern
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Carrier Proteins / metabolism*
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Cell Nucleus / metabolism
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Centrifugation, Density Gradient
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Cytoplasm / metabolism
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Fluorescent Antibody Technique, Indirect
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Fungal Proteins / metabolism
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Microscopy, Fluorescence
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Models, Genetic
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Molecular Sequence Data
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Nuclear Proteins
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Oligonucleotides / pharmacology
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Protein Structure, Tertiary
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RNA, Ribosomal / metabolism
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RNA, Ribosomal, 18S / metabolism*
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Ribosomes / metabolism
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Saccharomyces cerevisiae Proteins*
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Sequence Homology, Amino Acid
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Sucrose / pharmacology
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Time Factors
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Two-Hybrid System Techniques
Substances
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Carrier Proteins
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Fungal Proteins
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NOB1 protein, S cerevisiae
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Nuclear Proteins
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Oligonucleotides
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RNA, Ribosomal
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RNA, Ribosomal, 18S
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Saccharomyces cerevisiae Proteins
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Sucrose