Lipid droplet-associated protein that maintains the balance between lipogenesis and lipolysis and also regulates fatty acid oxidation in oxidative tissues. Recruits mitochondria to the surface of lipid droplets and is involved in lipid droplet homeostasis by regulating both the storage of fatty acids in the form of triglycerides and the release of fatty acids for mitochondrial fatty acid oxidation. In lipid droplet triacylglycerol hydrolysis, plays a role as a scaffolding protein for three major key lipolytic players: ABHD5, PNPLA2 and LIPE. Reduces the triacylglycerol hydrolase activity of PNPLA2 by recruiting and sequestering PNPLA2 to lipid droplets. Phosphorylation by PKA enables lipolysis probably by promoting release of ABHD5 from the perilipin scaffold and by facilitating interaction of ABHD5 with PNPLA2. Also increases lipolysis through interaction with LIPE and upon PKA-mediated phosphorylation of LIPE. Homooligomer. Interacts with PNPLA2; prevents interaction of PNPLA2 with ABHD5. Interacts with ABHD5; targets ABHD5 to lipid droplets and promotes interaction of ABHD5 with PNPLA2. Interacts with LIPE. Lipid droplet surface-associated (PubMed:17234449, PubMed:17130488, PubMed:16571721). Exchanges between lipid droplets and the cytoplasm (PubMed:19717842). Highly expressed in oxidative tissues, including heart, liver, brown adipose tissue (BAT) and slow-twitch fibers of skeletal muscle. Lower expression in epididymal white adipose tissue and anterior tibialis and quadriceps. Expressed in adrenal glands. Isoform 2 has the highest expression in heart. Up-regulated by fasting, PPARD, PPARA and PLIN4. Increased in muscle of high-fat diet fed mice. Induced by unsaturated long chain fatty acid in muscle. Phosphorylated by PKA. Phosphorylated on serine in skeletal muscle at rest or with lipolytic stimulation. No visible phenotype. Mice lack detectable lipid droplets in heart. The triacylglycerol and fatty acid content in heart is lower. Belongs to the perilipin family.