perilipiinia

Perilipinia is the term used to refer to the perilipin family of proteins that coat lipid droplets in adipocytes and other cell types and regulate lipid storage and mobilization. In mammals, the family includes PLIN1 through PLIN5, commonly known as perilipin-1, adipose differentiation-related protein (ADRP/PLIN2), tail-interacting protein of 47 kDa (TIP47/PLIN3), perilipin-4 (PLIN4, also called S3-12), and PLIN5 (also known as OXPAT). These proteins form part of the PAT family, named from perilipin, ADRP, and TIP47.

Localization and structure: Perilipins are cytosolic proteins that associate with the surface of cytoplasmic lipid droplets. They display tissue-specific expression patterns, with PLIN1 being highly enriched in adipose tissue. Their attachment to lipid droplets is mediated by amphipathic regions and lipid-binding motifs, enabling them to regulate the droplet surface and interact with lipolytic enzymes.

Function: Perilipins regulate access of lipases to triglycerides stored within lipid droplets. In resting cells, they protect droplets from untimely lipolysis. Upon hormonal stimulation (for example, catecholamines) activating the cAMP–PKA pathway, PLIN1 and related perilipins are phosphorylated at key serine residues. This phosphorylation promotes recruitment and activation of adipose triglyceride lipase (ATGL) via CGI-58/ABHD5 and hormone-sensitive lipase (HSL), facilitating triglyceride breakdown and fatty acid release.

Physiology and clinical relevance: Perilipins are central to whole-body energy homeostasis and tissue lipid metabolism. Altered perilipin function or expression is associated with metabolic conditions such as obesity, insulin resistance, and fatty liver disease. Mutations in PLIN1 can cause familial partial lipodystrophy type 4, illustrating the clinical importance of this protein family.