[Biological regulation with platelet activating factor--molecular cloning and signal transduction of PAF].

The cDNA encoding the platelet-activating factor (PAF) receptor was cloned from a guinea pig lung cDNA library by using a Xenopus laevis oocyte expression system. In the CHO cells which expressed guinea-pig PAF receptor, PAF triggered production of inositol phosphates, the release of arachidonic acid, and inhibited cyclic AMP accumulation. PAF also activated mitogen-activated protein (MAP) kinase and MAP kinase kinase in the CHO cells. These effects were partially regulated by pertussis toxin-sensitive G proteins. The analysis of the human PAF receptor gene revealed that it contains no intron in its coding region, but introns are distributed in the 5'-untranslated region. Two 5'-noncoding exons were identified, which are alternatively spliced to a common splice acceptor site on the third exon to yield two different species of functional mRNA. Existence of distinct promoters may regulated the PAF receptor gene expression in different tissues and cells.