GTP regulation of platelet-activating factor binding to human neutrophil membranes

Radiolabeled ligand binding studies showed that specific receptors for platelet-activating factor are present in human neutrophil membranes. GTP at 10(-7) to 10(-3) M decreased the specific binding of platelet-activating factor to neutrophil membranes in a dose-dependent manner. Inhibition of platelet-activating factor binding was also induced by other guanine nucleotides but not by adenine nucleotides. Our results suggest that platelet-activating factor receptor in human neutrophil membranes may be coupled to a guanine nucleotide binding protein.