Summary: A family of vertebrate and insect lipid droplet associated proteins. They consist of a conserved N-terminal PAT domain (an alpha-helical region of about 110 amino acids), an 11-mer repeat region, and lipid-binding hydrophobic regions or 4-helix bundles near their C-termini. Perilipins transiently or constitutively localize to LIPID DROPLETS in ADIPOCYTES and FOAM CELLS, especially in regions adjacent to the PLASMA MEMBRANE and ENDOPLASMIC RECTICULUM. They are critical for lipid droplet synthesis and homeostasis as well as the regulation of lipid metabolism. Genetic variations in perilipins are associated with ATHEROSCLEROSIS; OBESITY; and DIABETES MELLITUS.