Abstract
In eukaryotes, the ubiquitin-proteasome system plays a major role in selective protein breakdown for cellular regulation. Here we report the discovery of a new essential component of this degradation machinery. We found the Saccharomyces cerevisiae protein Cic1 attached to 26S proteasomes playing a crucial role in substrate specificity for proteasomal destruction. Whereas degradation of short-lived test proteins is not affected, cic1 mutants stabilize the F-box proteins Cdc4 and Grr1, substrate recognition subunits of the SCF complex. Cic1 interacts in vitro and in vivo with Cdc4, suggesting a function as a new kind of substrate recruiting factor or adaptor associated with the proteasome.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Carrier Proteins / genetics
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Carrier Proteins / metabolism*
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Cell Cycle Proteins / metabolism*
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F-Box Proteins*
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F-Box-WD Repeat-Containing Protein 7
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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Humans
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Molecular Sequence Data
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Peptide Hydrolases / metabolism*
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Peptide Synthases / metabolism*
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Proteasome Endopeptidase Complex*
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SKP Cullin F-Box Protein Ligases
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Saccharomyces cerevisiae Proteins*
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Substrate Specificity
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Ubiquitin-Protein Ligases*
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Ubiquitins
Substances
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Carrier Proteins
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Cell Cycle Proteins
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Cic1 protein, S cerevisiae
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F-Box Proteins
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F-Box-WD Repeat-Containing Protein 7
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FBXW7 protein, human
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Fungal Proteins
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Saccharomyces cerevisiae Proteins
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Ubiquitins
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GRR1 protein, S cerevisiae
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SKP Cullin F-Box Protein Ligases
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Ubiquitin-Protein Ligases
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Peptide Hydrolases
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Proteasome Endopeptidase Complex
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ATP dependent 26S protease
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Peptide Synthases