Effect of exogenously added acylphosphatases on inositol lipid metabolism in human platelets.

In this paper we demonstrate that human platelets contain an acylphosphatase isoenzyme. We then investigated the effect of exogenously added human muscle and erythrocyte acylphosphatases on inositol lipid content in human platelets permeabilized with saponin. Alterations in the level of the polyphosphoinositides were observed: in particular, the levels of phosphatidylinositol 4,5-bisphosphate, and of phosphatidylinositol 4-monophosphate were decreased, whereas the level of phosphatidylinositol was increased. These results suggest that acylphosphatases promote polyphosphoinositide dephosphorylation, possibly through intracellular Ca2+ mobilization.