GENERATION OF THE PRECURSOR (LYSO-PAF) OF PLATELET-ACTIVATING-FACTOR VIA A COA-DEPENDENT TRANSACYLASE

The microsomal fraction from rat spleen was shown to possess a CoA-dep endent transacylase activity that produced 1-[H-3]alkyl-2-lyso-sn-glyc ero-3-phosphocholine ([H-3]lyso-PAF), the immediate precursor of PAF i n the remodeling pathway of biosynthesis, from 1-[H-3]alkyl-2-acyl-sn- glycero-3-phosphec. This CoA-dependent transacylase did not require AT P or metal ions for activity making it unlikely that either acyl-CoA-s ynthetase or a Ca2+-dependent phospholipase A(2) were involved in the generation of [H-3]lyso-PAF. Albumin, in addition to CoA, was required to demonstrate the formation of [H-3]lyso-PAF from 1-[H-3]alkyl-2-acy l-sn-glyco-3-phosphocholine. It appeared that a major function of albu min in the incubations was to complex the [H-3]lyso-PAF formed, thus r emoving this end-product from the reaction. (C) 1995 Academic Press, I nc.