EVIDENCE FOR BIOSYNTHESIS OF PLASMENYLCHOLINE FROM PLASMENYLETHANOLAMINE IN HL-60 CELLS

Both [H-3]plasmenylethanolamine and [H-3]plasmenylcholine were produced from substrates of [H-3]alk-1-enylglycerol and [H-3]alk-1-enyllysoglycerophosphoethanolamine by intact HL-60 cells. Molecular species analysis of the [H-3]plasmenylcholine and [H-3]plasmenylethanolamine formed indicated the major portion of plasmenylcholine originates from plasmenylethanolamine by a series of reactions catalyzed by phospholipase A2, lysophospholipase D, acyltransferase, phosphohydrolase, and cholinephosphotransferase. However, a significant but much smaller portion of the plasmenylcholine appeared to be synthesized from plasmenylethanolamine via a direct base-exchange or a coupled phospholipase C/cholinephosphotransferase reaction.