Perilipin is a protein that coats lipid droplets in adipocytes, the fat-storing cells in adipose tissue. Perilipin acts as a protective coating from the body’s natural lipases, such as hormone-sensitive lipase,which break triglycerides into glycerol and free fatty acids for use in metabolism, a process called lipolysis.

Perilipin is hyperphosphorylated by PKA following β-adrenergic receptor activation. Phosphorylated perilipin changes conformation, exposing the stored lipids to hormone-sensitive lipase-mediated lipolysis. Although PKA also phosphorylates hormone-sensitive lipase, which can increase PKA activity, the more than 50-fold increase in fat mobilization (triggered by epinephrine) is primarily due to perilipin phosphorylation.