Document Detail

Further characterization of a Chinese hamster ovary cell mutant defective in lanosterol demethylation.
MedLine Citation:
PMID:  7066308     Owner:  NLM     Status:  MEDLINE    
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.
D J Berry; T Y Chang
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochemistry     Volume:  21     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  1982 Feb 
Date Detail:
Created Date:  1982-06-14     Completed Date:  1982-06-14     Revised Date:  2010-04-06    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  573-80     Citation Subset:  IM    
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MeSH Terms
Carbon Radioisotopes
Cell Line
Chromatography, Gas
Chromatography, Thin Layer
Cytochrome P-450 Enzyme System*
Lanosterol / metabolism*
Mixed Function Oxygenases / metabolism*
Oxidoreductases / metabolism*
Grant Support
Reg. No./Substance:
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 14-demethylase; EC monooxygenase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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