Platelet-activating factor acetylhydrolases are structurally diverse isoenzymes that catalyze
the hydrolysis of the acyl group at the second position of glycerol in unusual, bioactive
phospholipids (Fig. 1). Thus, as categorized by enzymatic activity, they are phospholipases
A2 (Groups VII and VIII, Ref. 1), which often initiate signal transduction and are regulated by
the state of the cell activation. However, the platelet-activating factor (PAF, 1 1-O-alkyl-2-
acetyl-sn-glycero-3-phosphocholine) acetylhydrolases have the opposite role; they were …