Abstract
The nin1-1 mutant of Saccharomyces cerevisiae cannot perform the G1/S and G2/M transitions at restrictive temperatures. At such temperatures, nin1-1 strains fail to activate histone H1 kinase after release from alpha factor-imposed G1 block and after release from hydroxyurea-imposed S block. The nin1-1 mutation shows synthetic lethality with certain cdc28 mutant alleles such as cdc28-IN. Two lines of evidence indicate that Nin1p is a component of the 26S proteasome complex: (i) Nin1p, as well as the known component of the 26S proteasome, shifted to the 26S proteasome peak in the glycerol density gradient after preincubation of crude extract with ATP-Mg2+, and (ii) nin1-1 cells accumulated polyubiquitinated proteins under restrictive conditions. These results suggest that activation of Cdc28p kinase requires proteolysis. We have cloned a human cDNA encoding a regulatory subunit of the 26S proteasome, p31, which was found to be a homolog of Nin1p.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Biopolymers / metabolism
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CDC28 Protein Kinase, S cerevisiae / metabolism*
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Cell Division / genetics
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Cell Division / physiology
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Enzyme Activation
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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Gene Expression Regulation, Fungal
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Genes, Fungal
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Genes, Lethal
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Humans
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Molecular Sequence Data
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Mutation
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Peptide Hydrolases / genetics
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Peptide Hydrolases / metabolism*
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Polyubiquitin
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Proteasome Endopeptidase Complex*
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Proteins / genetics
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Rats
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins*
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Sequence Homology, Amino Acid
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Ubiquitins / metabolism
Substances
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Biopolymers
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Fungal Proteins
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PSMD8 protein, human
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Proteins
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RPN12 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Ubiquitins
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Polyubiquitin
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CDC28 Protein Kinase, S cerevisiae
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Peptide Hydrolases
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Proteasome Endopeptidase Complex
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ATP dependent 26S protease