Molecular cloning of cDNAs encoding alpha1, alpha2, and beta subunits of rat brain platelet-activating factor acetylhydrolase.

Brain intracellular platelet-activating factor acetylhydrolase (PAF-AH(Ib)) is a tertiary G-protein-complex-like heterotrimeric enzyme which is composed of alpha1, alpha2, and beta subunits and is implicated in stages of brain development such as the formation of the brain cortex. We have isolated and sequenced cDNA clones encoding these three subunits of rat brain PAF-AH(Ib). The amino acid sequences of brain PAF-AH has shown an extremely high homology among mammalian species. The tissue distribution of the three subunits was examined by Northern blot analysis. Although the mRNAs were detected in various organs, the ratio of the level of mRNA expression for the three subunits differed among rat tissues, raising the possibility that isoform(s) other than the heterotrimeric isoform exist in certain tissues.