Abstract
A major eukaryotic proteolytic system is known to require the covalent attachment of ubiquitin to substrates prior to their degradation, yet the proteinase involved remains poorly defined. The proteasome, a large conserved multi-subunit protein complex of the cytosol and the nucleus, has been implicated in a variety of cellular functions. It is shown here that a yeast mutant with a defective proteasome fails to degrade proteins which are subject to ubiquitin-dependent proteolysis in wild-type cells. Thus, the proteasome is part of the ubiquitin system and mediates the degradation of ubiquitin-protein conjugates in vivo.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Base Sequence
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Cell Nucleus / enzymology
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Cysteine Endopeptidases / genetics
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Cysteine Endopeptidases / metabolism*
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Cytosol / enzymology
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Kinetics
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Molecular Sequence Data
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Multienzyme Complexes / genetics
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Multienzyme Complexes / metabolism*
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Mutagenesis, Site-Directed
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Oligodeoxyribonucleotides
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Polymerase Chain Reaction
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Proteasome Endopeptidase Complex
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Recombinant Fusion Proteins / metabolism
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Saccharomyces cerevisiae / enzymology*
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Saccharomyces cerevisiae / genetics
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Ubiquitins / genetics
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Ubiquitins / metabolism*
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beta-Galactosidase / genetics
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beta-Galactosidase / metabolism
Substances
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Multienzyme Complexes
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Oligodeoxyribonucleotides
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Recombinant Fusion Proteins
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Ubiquitins
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beta-Galactosidase
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Cysteine Endopeptidases
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Proteasome Endopeptidase Complex