Phosphatidylserine and phorbol myristate acetate stimulation of human lymphocyte guanylate cyclase.

Guanylate cyclase activities of human lymphocyte membrane and cytosol preparations are stimulated up to three-fold by the direct addition of phosphatidylserine. Phorbol 12-myristate 13-acetate (PMA) greatly augments the effect of phosphatidylserine, but has only a small effect when added alone. Stimulation involves an increase in Vmax, with no change in Km. Inhibitor studies suggest that stimulation may be mediated by protein kinase C, but not by phospholipase or lipoxygenase.