lipiddropletassociated

Lipid droplet–associated refers to proteins and other molecules that localize to lipid droplets (LDs), which are cytoplasmic organelles that store neutral lipids such as triglycerides and cholesteryl esters. LD-associated proteins regulate the formation, growth, and mobilization of these droplets and coordinate lipid storage with cellular energy needs.

A prominent group of LD-associated proteins belongs to the PAT (perilipin) family, including PLIN1, PLIN2 (adipophilin), PLIN3 (TIP47), PLIN4, and PLIN5. These proteins line the surface of LDs and control access of lipases to the droplet core, thereby modulating lipolysis. Other enzymes and cofactors, such as adipose triglyceride lipase (ATGL/PNPLA2) and its coactivator CGI-58 (ABHD5), are recruited to LDs in ways that influence triglyceride breakdown. Additional LD-associated proteins participate in LD biogenesis, trafficking, and interactions with other organelles, including mitochondria and autophagosomes.

Targeting to the LD surface often involves amphipathic helices, hydrophobic lipid-binding domains, and specific protein–protein interactions. The association of LD proteins is dynamic, changing in response to nutritional status, hormonal signals, and cellular stress, which in turn affects lipid storage, mobilization, and energy homeostasis.

Dysregulation of LD-associated proteins is linked to metabolic diseases such as obesity, hepatic steatosis, and lipodystrophies. Research in this area employs proteomics, imaging, and functional assays to elucidate mechanisms of LD biology and inter-organelle communication.