Interfacial conformation of dipalmitoylglycerol and dipalmitoyl-phosphatidylcholine in phospholipid bilayers

Diacylglycerols are minor constituents of membrane lipids, yet are essential in the activation and membrane association of protein kinase C. Solid-state super(13)C NMR experiments have been used to characterize the orientation of the glycerol backbone of dipalmitoylglycerol (DPG) and dipalmitoyl-phosphatidylcholine (DPPC) in egg phosphatidylcholine (PC) bilayers. The data suggest that the time-averaged orientation of the glycerol backbone is tilted from the bilayer normal, in contrast to the nearly parallel orientation observed in the crystal structures of phosphatidylcholines and phosphatidylethanolamines or the perpendicular orientation observed in the crystal structures of diacylglycerols.