Phosphatidylinositol-specific phospholipase D: a pathway for generation of a second messenger.

We have found a phospholipase D activity in the postnuclear fraction of human neutrophils which is stimulated by incubation of cells with the calcium ionophore A23187. The phospholipase D activity was assessed by both phosphatidate formation and free inositol release from phosphatidylinositol substrate. The phospholipase D activity shows an optimum pH of 7.5 and hydrolyzes specifically phosphatidylinositol. These results suggest that this phosphatidylinositol-specific phospholipase D can play a role in cell activating process.