Direct Evidence that Cholesterol Ester Hydrolase from Adrenal Cortex is the Same Enzyme as Hormone‐Sensitive Lipase from Adipose Tissue

Abstract

Several properties of the cytosolic cholesterol ester hydrolase from bovine adrenal cortex were investigated and those properties were compared directly with those of the well-characterized hormone-sensitive lipase, the rate-limiting enzyme in adipose tissue lipolysis. Properties examined included: activity against different substrates; susceptibility to inhibition by NaF, Hg2+ ions and diisopropyl fluorophosphonate; subunit MW as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate; ability to serve as a substrate for cAMP-dependent protein kinase; effect of phosphorylation on enzyme activity; and degradation pattern of polypeptides following limited proteolysis. In all respects the 2 enzymes exhibited essentially identical characteristics. The same protein, or 2 very similar proteins, apparently catalyzes the hydrolysis of cholesterol esters in adrenal cortex and lipolysis in adipose tissue. The implication of this finding is discussed in relation to the hormonal control of steroidogenesis in adrenal cortex and of lipolysis of adipose tissue.