Radioimmune precipitation of 3-hydroxy-3-methylglutaryl coenzyme A reductase from Chinese hamster fibroblasts. Effect of 25-hydroxycholesterol.
Antibody prepared against 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase of rat liver can be shown to inhibit this enzyme in extracts prepared from cultured Chinese hamster ovary (CHO-K1) cells. The molecular weight (53,000) of the HMG-CoA reductase subunits of rat liver and Chinese hamster liver is identical with a [35S]methionine-labeled polypeptide that can be precipitated from CHO-K1 lysates by this antibody used in conjunction with protein A Sepharose. It is shown that 25-hydroxycholesterol which lowers HMG-CoA reductase activity in cultured fibroblasts blocks the incorporation of labeled methionine into this polypeptide. Furthermore, the antibody immune precipitates two other polypeptides with molecular weights of 127,000 and 60,000. The latter polypeptide responds to 25-hydroxycholesterol in the same fashion as the 53,000-dalton polypeptide. In a dominant 25-hydroxycholesterol-resistant mutant of the CHO-K1 cell, 25-hydroxycholesterol did not inhibit incorporation of labeled methionine into either the 53,000- or 60,000-dalton polypeptides.
D000818:Animals; D000936:Antigen-Antibody Complex; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D006888:Hydroxycholesterols / Q000494:pharmacology*; D006903:Hydroxymethylglutaryl CoA Reductases / Q000302:isolation & purification / Q000378:metabolism*; D007106:Immune Sera; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D010053:Ovary
D000936:Antigen-Antibody Complex; D006888:Hydroxycholesterols; D007106:Immune Sera; D046911:Macromolecular Substances; C007997:25-hydroxycholesterol; D006903:Hydroxymethylglutaryl CoA Reductases