Perilipin

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Perilipin is a protein that coats lipid droplets in adipocytes^[1], the fat-storing cells in adipose tissue. Perilipin acts as a protective coating from the body’s natural lipases, such as hormone-sensitive lipase, that 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 would also phosphorylate hormone-sensitive lipase, which could double or triple PKA's activity, but the more than 50-fold increase in fat mobilization (triggered by epinephrine) is primarily due to perilipin phosphorylation.

Perilipin is an important regulator of lipid storage. Perilipin expression is elevated in obese animals and humans. Perilipin-null mice eat more food than wild-type mice, but gain 1/3 less fat than wild-type mice on the same diet; Perilipin-null mice are thinner, with more lean muscle mass. Perilipin-null mice also exhibit enhanced leptin production and a greater tendency to develop insulin resistance than wild-type mice. Polymorphisms in the human perilipin (PLIN) gene, 13041A>G and 14995A>T, have been associated with increased risk of obesity in women. The PLIN polymorphism 11482G>A has been associated with decreased perilipin expression and increased lipolysis in women.