Activation of 85 kDa PLA2 by Eicosanoids in Human Neutrophils and Eosinophils
The initial step in the remodeling pathway of PAF synthesis is catalyzed by phospholipase A2 (PLA2).1 It has generally been accepted that PLA2 acts directly on 1-0-alkyl-2-arachidonoyl-sn-glycero-3-phosphocholine (alkyl-2-AA-GPC) to form lyso-PAF (1-alkyl-2-lyso-GPC) which is then acetylated to yield PAF. More recent studies suggest that PAF synthesis may also be initiated indirectly through the action of CoA-independent transacylase following the hydrolysis of l-0-alk-1′-enyl-2-AA-sn-glycero-3-phosphoethanolamine (alkenyl-2-AA-GPE) by PLA2.2,3 In the putative indirect pathway, an accumulation of alkenyl-2-lyso-GPE triggers the transfer of AA from alkyl-2-AA-GPC to the alkenyl-2-lyso-GPE thus forming lyso-PAF. It seems logical that both the direct and indirect pathways may contribute to PAF synthesis. However, the relative physiological importance of the two pathways has not been established.
KeywordsHuman Neutrophil Arachidonic Acid Release Lipoxygenase Product Free Arachidonic Acid Pancreatic PLA2
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