Adipose triglyceride lipase (ATGL) is a 504 amino acid protein that is highly expressed in mouse and human adipose tissue. ATGL is catalyzes the initial step in triglyceride hydrolysis in adipocyte lipid droplets and has acylglycerol transacylase activity. Inhibition of ATGL markedly decreases total adipose acyl-hydrolase activity. Thus, ATGL and hormone-sensitive lipase coordinately catabolize stored triglycerides in adipose tissue of mammals.