Evidence for biosynthesis of plasmenylcholine from plasmenylethanolamine in HL-60 cells.

Both [3H]plasmenylethanolamine and [3H]plasmenylcholine were produced from substrates of [3H]alk-1-enylglycerol and [3H]alk-1-enyllysoglycerophosphoethanolamine by intact HL-60 cells. Molecular species analysis of the [3H]plasmenylcholine and [3H]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.