title: The role of lysophosphatidylcholine in lipid synthesis by developing sunflower (Helianthus annuus L.) seed microsomes.
abstract: The incorporation of oleate from oleoyl-CoA into lipids by microsomes from developing sunflower (Helianthus annuus L.) seeds has been investigated. Oleate was incorporated mainly into position 2 of phosphatidylcholine or released as free fatty acid. The addition of exogenous 1-acyl-lysophosphatidylcholine increased the incorporation of oleate into position 2 of phosphatidylcholine and decreased the release of free oleate. In the absence of exogenous lysophosphatidylcholine, the incorporation of oleate into phosphatidylcholine was limited by the amount of endogenous acceptor present. DH-990, an inhibitor of acyl-CoA:lysophosphatidylcholine acyltransferase, almost completely inhibited the incorporation of oleate from oleoyl-CoA into phosphatidylcholine at a concentration of 2.5 mM. These results indicate that the incorporation of oleate from oleoyl-CoA into microsomal phosphatidylcholine occurs mainly by the acylation of a 1-acyl-lysophosphatidylcholine acceptor rather than by acyl exchange between oleoyl-CoA and phosphatidylcholine. While the incorporation of oleoyl-CoA was completed within 2 to 5 min, exogenous 1-acyl-lysophosphatidylcholine was incorporated into phosphatidylcholine for up to 30 min. Addition of oleoyl-CoA resulted in an increase in both the rate and magnitude of lysophosphatidylcholine incorporation, which could not be accounted for by a stoichiometric reaction between the two substrates. Evidence is provided that free CoA had an independent stimulatory effect on the incorporation of lysophosphatidylcholine. The implications of this finding are discussed.
mesh_terms: D008243:1-Acylglycerophosphocholine O-Acyltransferase / Q000037:antagonists & inhibitors; D000214:Acyl Coenzyme A / Q000378:metabolism; D002208:Caproates / Q000494:pharmacology; D006368:Helianthus / Q000378:metabolism* / Q000648:ultrastructure; D008055:Lipids / Q000096:biosynthesis*; D008244:Lysophosphatidylcholines / Q000502:physiology*; D008861:Microsomes / Q000378:metabolism; D019301:Oleic Acid; D009829:Oleic Acids / Q000378:metabolism; D012639:Seeds / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D000214:Acyl Coenzyme A; D002208:Caproates; D008055:Lipids; D008244:Lysophosphatidylcholines; D009829:Oleic Acids; C017585:oleoyl-coenzyme A; D019301:Oleic Acid; C012656:DH 990; D008243:1-Acylglycerophosphocholine O-Acyltransferase