Acyltransferase-catalyzed cleavage of arachidonic acid from phospholipids and transfer to lysophosphatides in macrophages derived from bone marrow. Comparison of different donor- and acceptor substrate combinations.

In a previous paper it was shown that in prelabeled murine thymocytes a direct CoA-mediated transfer of arachidonic acid from phosphatidylcholine to lysophosphatidylethanolamine occurs which does not involve the intermediate formation of free fatty acid. The transfer is ATP-independent and is catalyzed by the acyl-CoA: lysophosphatide acyltransferase operating in reverse. In prelabeled thymocytes phosphatidylcholine was the only arachidonoyl donor and lysophosphatidylethanolamine the only lysoacceptor. In murine bone-marrow-derived macrophages a series of CoA-mediated transfer reactions were detected leading to a redistribution of arachidonic acid between phospholipids. Using exogenous substrates a bidirectional transfer from 1-acyl-2-arachidonoylglycerophosphocholine to lysophosphatidylethanolamine occurs. An unidirectional transfer from 1-acyl-2-arachidonoylglycerophosphoinositol to lysophosphatidylcholine and from 1-acyl-2-arachidonoylglycerophosphoinositol to lysophosphatidylethanolamine was observed. Plasmalogenic lysoacceptors generally have a weaker acceptor capacity than the correspondent acyllysophospholipid. In macrophages the CoA-mediated transfer of arachidonoyl moieties is independent of ATP and Mg2+ and is totally inhibited by sodium cholate, indicating that it is catalyzed by the acyl-CoA: lysophosphatide acyltransferase.