PLIN4

PLIN4, or perilipin-4, is a member of the perilipin family of lipid droplet–associated proteins. In humans it is encoded by the PLIN4 gene. Perilipins coat the surface of intracellular lipid droplets in adipocytes and other cell types and regulate the storage and mobilization of triglycerides.

PLIN4 localizes to lipid droplets through a lipid droplet targeting motif and shares conserved motifs with other perilipins. Its precise expression pattern varies by tissue, with detectable levels in adipose tissue and in other metabolically active tissues.

Functionally, the PLIN proteins regulate lipolysis by modulating access of lipases to triglyceride stores. In resting cells, perilipins help protect lipid droplets from nonspecific lipase activity; upon hormonal stimulation (for example, catecholamine signaling leading to PKA activation), phosphorylation of perilipins induces conformational changes that promote lipolysis by activating adipose triglyceride lipase and related enzymes.

Regulation and interactions indicate that PLIN4 expression and activity are influenced by nutritional and hormonal states. Like other PLINs, PLIN4 is believed to interact with co-regulatory proteins that coordinate lipolysis, although the exact partners and mechanisms for PLIN4 specifically are still under investigation.

Clinical significance, in turn, focuses on PLIN4’s role in lipid droplet metabolism and potential involvement in metabolic conditions such as obesity and insulin resistance. Compared with other perilipins, the precise contribution of PLIN4 to lipid mobilization remains an area of active study.

See also: perilipin family; lipid droplets.