Hormone-sensitive lipase (EC3.1.1.79, HSL), also previously known as cholesteryl ester hydrolase (CEH),[5] sometimes referred to as triacylglycerol lipase, is an enzyme that, in humans, is encoded by the LIPEgene,[6] and catalyzes the following reaction:
(1) diacylglycerol + H2O = monoacylglycerol + a carboxylate
(2) triacylglycerol + H2O = diacylglycerol + a carboxylate
(3) monoacylglycerol + -H2O = glycerol + a carboxylate
HSL is an intracellular neutral lipase capable of hydrolyzing a variety of esters.[7] The enzyme has a long and a short form. The long form is expressed in steroidogenic tissues such as testis, where it converts cholesteryl esters to free cholesterol for steroid hormone production. The short form is expressed in adipose tissue, among others, where it hydrolyzes stored triglycerides to free fatty acids.[8]