ABSTRACT
The alkyl and alk-1-enyl types of ether-linked phospholipids are present in mammalian cells almost exclusively as structural analogues of phosphatidylcholine and phosphatidylethanolamine. Perhaps the most significant discovery and advancement in studies of the ether-linked analogues of phosphatidylcholine was the elucidation of the chemical structure of platelet activating factor which was identified in 1979 as 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine. In contrast to the alkyl lipids that contain phosphocholine, only limited knowledge is available about the origin of the alk-1-enyl moiety of plasmenylcholine. Warner and Lands117 first demonstrated that lysoplasmenylcholine hydrolase in rat liver microsomes catalyzes the hydrolysis of lysoplasmenylcholine to produce free aldehydes and glycerophosphocholine. Platelet activating factor is inactivated by hydrolysis of the acetate moiety via a reaction catalyzed by an acetylhydrolase. Regulation of the enzymatic steps that catalyze the de novo synthesis of plasmanylcholines from 1-alkyl-2-lyso-GroP is poorly understood.
