The long term goals are to identify and characterize the individual molecular steps of glycerolipid metabolism and to elucidate the mechanisms which function to ensure that the appropriate quantities and types of glycerolipids are produced to meet the demands for bioregulators, for membrane biogenesis and maintenance, for lipoprotein and bilayer formation, and energy storage. The first of two specific aims focuses on the role of sn-1,2-diacylglycerols as bioregulators of protein kinase C and seeks to fill in gaps in knowledge about the transmembrane movement, intermembrane translocation, and metabolism of sn-1,2-diacylglycerols containing long chain and short chain fatty acids. Diacylglycerol analogues and E. coli diacyglycerol kinase will be used to investigate the location and transmembrane movement of diacylglycerols in vitro. Methods to deliver sn-1,2-diacylglycerols containing long chain fatty acids to cells will be developed, and then employed to investigate metabolism and translocation. These studies are related to mechanism of hormone action, transmembrane signaling, regulation of hormone receptors, tumor promotion, mechanism of oncogene product action, cell growth and differentiation. The second specific aim will test the hypothesis that a specific protien facilitates the transmembrane movement of phosphatidycholine in the endoplasmic reticulum. This fundamental step in membrane bilayer formation and lipid sorting will be investigated using new methods based on the uptake of dibutyrylphosphatidylcholine, which is soluble, and, therefore, permits the usual transport methods to be employed. Kinetic analysis will be performed. Exit and entrance counterflow will be investigated, substrate specificity will be examined, and a search for inhibitors will be undertaken. The relationship of dibutyrylphosphatidylcholine transport in microsomes and that of phosphatidylcholine transmembrane movement will be established using the inhibitors developed and several assays. Studies aimed at identifying the specific transport protein will be performed. Analogous studies on phosphatidylethanolamine and phosphatidylserine translocation wil be performed to ascertain whether separate systems exist. These are basic studies aimed at molecular analysis of bilayer formation, lipid sorting, and the generation of asymmetric bilayers.
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