| Further characterization of a Chinese hamster ovary cell mutant defective in lanosterol demethylation. | |
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MedLine Citation:
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PMID: 7066308 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Sensitive in vitro lanosterol 14 alpha- and 4 alpha-methylsterol oxidase assays, particularly suitable for cell extracts of tissue culture cells, were developed and validated. Using these assays, we showed that the biochemical lesion of mutant 215, a cholesterol-requiring Chinese hamster ovary cell auxotroph isolated and partially characterized previously [Chang, T. Y., Telakowski, C., Vanden Heuvel, W., Alberts, A. W., & Vagelos, P. R. (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 832-836], was localized at the 4 alpha-methylsterol oxidase enzyme system. The defect in 4 alpha-methylsterol oxidase activity in mutant 215 cells could be demonstrated by using either 4,4-dimethylcholestanol or 4 alpha-methylcholestanol as the substrate, suggesting that the enzyme systems responsible for 4 alpha-methyl- and 4,4-dimethylsterols may share a common component. However, demethylation of the C-14 alpha methyl group was found to occur at identical rates in wild-type and mutant 215, suggesting that C-14 alpha demethylation and C-4 alpha demethylation may occur by separate enzyme systems. A [3H]dihydrolanosterol incorporation experiment in intact cells of wild-type and mutant 215 supported these conclusions. Despite these results, a [14C]acetate pulse experiment indicated that [14C]lanosterol, instead of its 14C-labeled 14-demethylated sterol derivative(s), accumulated in intact cells of mutant 215. Possible implications of these findings for the mechanisms of lanosterol demethylation reactions are discussed. |
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Authors:
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D J Berry; T Y Chang |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Biochemistry Volume: 21 ISSN: 0006-2960 ISO Abbreviation: Biochemistry Publication Date: 1982 Feb |
Date Detail:
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Created Date: 1982-06-14 Completed Date: 1982-06-14 Revised Date: 2010-04-06 |
Medline Journal Info:
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Nlm Unique ID: 0370623 Medline TA: Biochemistry Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 573-80 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Carbon Radioisotopes Cell Line Chromatography, Gas Chromatography, Thin Layer Cricetinae Cricetulus Cytochrome P-450 Enzyme System* Female Kinetics Lanosterol / metabolism* Mixed Function Oxygenases / metabolism* Mutation* Ovary Oxidoreductases / metabolism* Tritium |
| Grant Support | |
ID/Acronym/Agency:
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HL 21246/HL/NHLBI NIH HHS; IP30 CA23108/CA/NCI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Carbon Radioisotopes; 10028-17-8/Tritium; 79-63-0/Lanosterol; 9035-51-2/Cytochrome P-450 Enzyme System; EC 1.-/Mixed Function Oxygenases; EC 1.-/Oxidoreductases; EC 1.14.13.70/sterol 14-demethylase; EC 1.14.13.72/methylsterol monooxygenase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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