出版社:American Society for Biochemistry and Molecular Biology
摘要:Lipid droplets are accumulations of neutral lipids surroundedby a monolayer of phospholipids and associated proteins. Recentproteomic analysis of isolated droplets suggests that they arepart of a dynamic organelle system that is involved in membranetraffic as well as packaging and distributing lipids in thecell. To gain a better insight into the function of droplets,we used a combination of mass spectrometry and NMR spectroscopyto characterize the lipid composition of this compartment. Inaddition to cholesteryl esters and triacylglycerols with mixedfatty acid composition, we found that 10–20% of the neutrallipids were the ether lipid monoalk(en)yl diacylglycerol. Althoughlipid droplets contain only 1–2% phospholipids by weight,>160 molecular species were identified and quantified. Phosphatidylcholine(PC) was the most abundant class, followed by phosphatidylethanolamine(PE), phosphatidylinositol, and ether-linked phosphatidylcholine(ePC). Relative to total membrane, droplet phospholipids wereenriched in lysoPE, lysoPC, and PC but deficient in sphingomyelin,phosphatidylserine, and phosphatidic acid. These results suggestthat droplets play a central role in ether lipid metabolismand intracellular lipid traffic.Supplementary key words lipid droplet • membranes • phospholipid turnover