Modulation of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity with intracellular fractions of hamster adrenals

Hamster adrenal HMG-CoA reductase activity was enhanced with rat liver cytosolic phosphorylase phosphatase as well as with similarly isolated beef and hamster adrenal cytosolic preparations. HMG-CoA reductase was inactivated when microsomes were incubated in an EDTA-free medium but containing MgCl 2 and ATP. The reductase activity of microsomes isolated from adrenals of hamsters sacrificed at 1100 h and 1900 h were (mean ± SEM, pmo1/mg protein/min.) 299.6±62.3 and 588.3 ± 96.6 respectively and could be enhanced by a factor of four when preincubated in the presence of liver phosphatase.