Use of pertussis toxin to investigate the mechanism of action of prostaglandin F2α on the corpus luteum in sheep

Abstract

ABSTRACT Pertussis toxin catalysed the ADP-ribosylation of a protein of Mr 40 000 in ovine luteal tissue. Ribosylation of 45% of this protein in whole cell incubations (as judged by subsequent ribosylation of cell-free preparations in the presence of [32P]NAD) attenuated the prostaglandin (PG)F2α-stimulated hydrolysis of [3H]inositol-labelled phosphatidylinositol-4,5-bisphosphate into inositol trisphosphate by 60%, but did not affect the inhibition by PGF2α of LH-stimulated accumulation of cyclic AMP. It is concluded that activation of phospholipase C by PGF2α involves a pertussis toxin-sensitive protein, probably a G protein, and that the inhibitory effect of PGF2α on LH-stimulated adenylate cyclase is unlikely to be directly mediated by such a protein.