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c-myc and c-myb protein degradation: effect of metabolic inhibitors and heat shock.

Lüscher, B and Eisenman, R N (1988) c-myc and c-myb protein degradation: effect of metabolic inhibitors and heat shock. Molecular and cellular biology, 8 (6). pp. 2504-2512. ISSN 0270-7306

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The proteins encoded by both viral and cellular forms of the c-myc oncogene have been previously demonstrated to have exceptionally short in vivo half-lives. In this paper we report a comparative study on the parameters affecting turnover of nuclear oncoproteins c-myc, c-myb, and the rapidly metabolized cytoplasmic enzyme ornithine decarboxylase. The degradation of all three proteins required metabolic energy, did not result in production of cleavage intermediates, and did not involve lysosomes or ubiquitin. A five- to eightfold increase in the half-life of c-myc proteins, and a twofold increase in the half-life of c-myb proteins was detected after heat-shock treatment at 46 degrees C. In contrast, heat shock had no effect on the turnover of ornithine decarboxylase. Heat shock also had the effect of increasing the rate of c-myc protein synthesis twofold, whereas c-myb protein synthesis was decreased nearly fourfold. The increased stability and synthesis of c-myc proteins led to an overall increase in the total level of c-myc proteins in response to heat-shock treatment. Furthermore, treatments which reduced c-myc and c-myb protein turnover, such as heat shock and exposure to inhibitors of metabolic energy production, resulted in reduced detergent solubility of both proteins. The recovery from heat shock, as measured by increased turnover and solubility, was energy dependent and considerably more rapid in thermotolerant cells.

Item Type: Article or Abstract
Additional Information: This article is freely available in PubMed Central and at the journal's website.
PubMed ID: 3043180
PMCID: PMC363451
Keywords or MeSH Headings: Animals; Antigen-Antibody Complex/analysis; Chickens; Half-Life; Heat; Lymphoma/metabolism; Molecular Weight; Proto-Oncogene Proteins/biosynthesis/immunology/metabolism; Proto-Oncogene Proteins c-myb; Proto-Oncogene Proteins c-myc; Proto-Oncogenes; Tumor Cells, Cultured;
Subjects: Molecules > Proteins
Molecules > Genes > Oncogenes
Depositing User: Library Staff
Date Deposited: 04 Dec 2008 19:09
Last Modified: 21 May 2010 22:36

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