Induction by lysophospholipids of CoA-dependent arachidonyl transfer between phospholipids in rat platelet homogenates.

Rat platelet homogenates are able to catalyze CoA-mediated, ATP-independent transfer of arachidonic acid from platelet phospholipids to added lysophospholipids. Homogenates of platelets prelabelled with radioactive arachidonic or oleic acid were incubated in the presence of CoA and various lysophospholipids. Transfer observed with arachidonic acid-labelled platelets was dependent on the lysophospholipid added. When 1-alkenyl- or 1-acyllysophosphatidylethanolamine was used, there was a more efficient arachidonyl transfer from phosphatidylcholine than from phosphatidylinositol to the phosphatidylethanolamine fraction. Lysophosphatidylserine also accepted arachidonyl from phosphatidylcholine. Addition of lysophosphatidylcholine resulted in a decrease in the labelling of phosphatidylinositol and to a lesser extent of phosphatidylethanolamine with concomitant transfer to phosphatidylcholine. Lysophosphatidylinositol and lysophosphatic acid did not act as substrate for this transfer reaction. Free, non-radioactive arachidonic acid did not compete for the labelled arachidonic acid transfer. This pathway may play a major role in the synthesis of arachidonyl species of phosphatidylethanolamine and phosphatidylserine and for the arachidonyl transfer to the phosphatidylethanolamine plasmologen in stimulated platelets.