The unveiling of the mechanisms of such a loss will potentially have clinical implications. Lipids, proteins and carbohydrates are the three major building components of all living organisms. Wogonoside lipids provide energy for daily usage and also function as signaling molecules in the regulation of important biological processes. To maintain proper physiological conditions, the metabolism and homeostasis of lipids must be precisely regulated. Defects in lipid metabolism can lead to health-threatening problems in humans, for example, obesity and insulin resistance. Within cells, neutral lipids, mainly triacylglycerol and cholesterol ester, are stored in a specific type of organelle, called the lipid droplet. Under nutrient-rich situations, excess fatty acids can be converted to TAG 9-methoxycamptothecine through lipogenesis and stored in lipid droplets. Under some nutrient limiting conditions such as starvation, lipids can be released from lipid droplets by lipolysis for cell usage. Maintaining the homeostasis of lipid droplets is therefore important for normal lipid metabolism and lipid-related diseases. Lipid droplets contain a lipid core and a monolayer of protein coated phospholipid membrane. The size and the content of lipid droplets are largely regulated by the balance of lipogenesis and lipolysis, which is mediated by many lipases. PAT domain proteins, the best known lipid drop let surface proteins, can interact with lipases. PAT proteins regulate the lipid droplet surface access of lipase to modulate the lipolysis process. Many fundamental aspects of the dynamics of lipid droplets, including their biogenesis, the transport of lipids in and out of lipid droplets, and intracellular trafficking of lipid droplets, are not well characterized. Identifying the proteins involved in these processes will lead to a better understanding of the dynamics of lipid droplets. Lipid droplets from different types of cells/tissues in several organisms have been purified and many proteomic studies have been conducted to identify proteins associated with them. These proteins are likely localized on the surface of lipid droplets and function directly in lipid droplet dynamics. Many members of the Rab small GTPase family have been associated with lipid droplets in proteomic studies.