Diurnal variation of HMG-CoA reductase activity in rat liver peroxisomes.
The specific activity of hepatic microsomal and peroxisomal 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) was determined at different times during a 24 hour cycle from cholestyramine treated rats. The microsomal HMG-CoA reductase activity displayed a peak at D-6 (6th hour of the dark cycle) as previously reported, whereas, the peroxisomal HMG-CoA reductase activity was the highest at L-2 (2nd hour of the light cycle). Immunoblots of the peroxisomal HMG-CoA reductase suggest that the increase in enzyme activity at L-2 is due to changes in enzyme mass. The different cyclic variations observed in microsomal and peroxisomal HMG-CoA reductase activity may suggest different mechanisms of regulation.
Department of Biology, San Diego State University, CA 92182.
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D000818:Animals; D002940:Circadian Rhythm; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D008793:Metrizamide / Q000494:pharmacology; D008830:Microbodies / Q000201:enzymology*; D008862:Microsomes, Liver / Q000201:enzymology; D051381:Rats; D011919:Rats, Inbred Strains
D006903:Hydroxymethylglutaryl CoA Reductases; D008793:Metrizamide