Role of PAT proteins in lipid metabolism.

One of the central reactions in bodily energy metabolism is lipolysis in adipocytes, the reaction that governs the release of stored fatty acids from the adipocyte triacylglycerol pool, which constitutes the major energy reserve in animals. These fatty acids are then transported by serum albumin to various tissues to supply their energy requirements. This reaction was previously thought to result from phosphorylation and activation of hormone-sensitive lipase by protein kinase A (PKA) but is now known to be governed by a translocation of the lipase from the cytosol to the surface of the intracellular lipid droplet that houses the reservoir of TAG. This droplet is coated with perilipin A, which is also phosphorylated by PKA in response to lipolytic stimuli, and phosphorylation of perilipin A is essential for HSL translocation and stimulated lipolysis.