Abstract
The tumor suppressor p53 is degraded by the ubiquitin-proteasome system. p53 was polyubiquitinated in the presence of E1, UbcH5 as E2 and MDM2 oncoprotein. A ubiquitin molecule bound MDM2 through sulfhydroxy bond which is characteristic of ubiquitin ligase (E3)-ubiquitin binding. The cysteine residue in the carboxyl terminus of MDM2 was essential for the activity. These data suggest that the MDM2 protein, which is induced by p53, functions as a ubiquitin ligase, E3, in human papillomavirus-uninfected cells which do not have E6 protein.
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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Cell Extracts
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HeLa Cells
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Humans
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Ligases / chemistry
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Ligases / metabolism*
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Molecular Sequence Data
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Nuclear Proteins*
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Proto-Oncogene Proteins / metabolism*
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Proto-Oncogene Proteins c-mdm2
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Sequence Analysis
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Tumor Suppressor Protein p53 / metabolism*
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Ubiquitin-Conjugating Enzymes
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Ubiquitins / metabolism*
Substances
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Cell Extracts
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Nuclear Proteins
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Proto-Oncogene Proteins
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Tumor Suppressor Protein p53
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Ubiquitins
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Ubiquitin-Conjugating Enzymes
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MDM2 protein, human
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Proto-Oncogene Proteins c-mdm2
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Ligases