High de novo synthesis of glycerolipids compared to deacylation-reacylation in rat liver microsomes.
A microsomal system characterized by high flux through the entire de novo pathway from glycerol phosphate to phosphatidylcholine and triacylglycerol has been developed. Optimum synthesis of phosphatidylcholine requires CDPcholine, Mg2+, KCl and a palmitoyl-CoA-generating system containing palmitic acid, ATP and CoA. Incorporation of [14C]glycerol phosphate into phosphatidylcholine/triacylglycerol synthesis ratio decreases as palmitate is increased. Phosphatidylcholine synthesis from glycerol phosphate is stimulated more by palmitate than by other saturated fatty acids; phosphatidylcholine synthesis increases with increasing unsaturation of the added fatty acids. The ratio of incorporation of [3H]palmitate to [14C]glycerol phosphate was determined for phosphatidic acid, diacylglycerol, phosphatidylcholine and triacylglycerol. This ratio is approximately 2 for all diacylglycerolipids and 3 for triacylglycerol. In our system, incorporation of palmitate into microsomal glycerolipid proceeds primarily by the de novo pathway, with minimal fatty acid recycling via deacylation-reacylation.
D000818:Animals; D005227:Fatty Acids / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005994:Glycerophosphates / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000096:biosynthesis; D010743:Phospholipids / Q000096:biosynthesis*; D051381:Rats; D013329:Structure-Activity Relationship; D014280:Triglycerides / Q000096:biosynthesis*
D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D005994:Glycerophosphates; D010713:Phosphatidylcholines; D010743:Phospholipids; D014280:Triglycerides; C029620:alpha-glycerophosphoric acid