Intracellular lipid storage droplets (LSDs) are unique organelles that store metabolic precursors; they contain different lipids [e.g. triacylglyceride (TAG) or cholesteryl ester (CE)] at their core, and their surface is coated with members of the perilipin family of proteins (Plins). Plins regulate lipid storage metabolism through the recruitment of lipases, and other regulatory proteins, to lipid droplet surfaces, and the loss of Plin activity can significantly reduce the intracellular lipid levels in adipocytes and hepatocytes. In mammals, there are five Plin genes as well as several splice variants, but it is not known whether they exert distinct functions. On page , Alan Kimmel and colleagues address this question and show that, within individual cells of various cell types, distinct Plins preferentially sequester to LPS pools that contain either TAGs or CEs, and can alter the relative intracellular TAG or CE levels towards the targeted lipid. For example, adipose and heart muscle, which predominantly accumulate TAGs, also express the Plins that favour TAG-containing lipopolysaccharides, whereas steroidogenic cells, which accumulate CE, express other distinct Plins. These results point to separate Plin functions that might have important implications for the pathogenesis associated with abnormal lipid storage.
