Hormone-sensitive Lipase/HSL: Proteins and Enzymes

Hormone-sensitive Lipase (HSL), also called LIPE, is an 84 kDa phosphoprotein that is the rate-limiting enzyme in the catalytic breakdown of triglycerides. The human 775 amino acid (aa) form is active in adipose tissue and skeletal muscle. HSL translocates to triglyceride-metabolizing lipid droplets in response to epinephrine or contraction in skeletal muscle, but to the cytosol following insulin treatment of adipocytes. A 120 kDa isoform of human HSL with a 301 aa N-terminal extension is present only in the testes, localized to elongating spermatids and spermatozoa.