PHOSPHATIDYLINOSITOL PHOSPHATE, PHOSPHATIDYLINOSITOL BISPHOSPHATE, AND THE PHOSPHOINOSITOL SPHINGOLIPIDS ARE FOUND IN THE PLASMA-MEMBRANE AND STIMULATE THE PLASMA-MEMBRANE H+-ATPASE OF SACCHAROMYCES-CEREVISIAE

Several plasma membrane phospholipids have been studied for their ability to modulate the activity of the plasma membrane H+-ATPase of Saccharomyces cerevisiae. We show here that phosphatidylinositol phosphate (PIP), phosphatidylinositol bisphosphate (PIP2), and/or the phosphatidylinositol and PIP kinases are localized primarily in the plasma membrane. Previous in vivo studies with S. cerevisiae have shown that large, rapid, and reversible changes occur in the levels of PIP and PIP2 congruent with changes in cellular ATP levels. We demonstrate here that isolated plasma membranes exhibit the same changes in PIP and PIP2 content when they are supplied with or washed free of ATP. Using a mixed micellar assay we systematically studied the efficacy of the plasma membrane lipids in sustaining the activity of the plasma membrane H+-ATPase. We demonstrate for the first time that a number of plasma membrane glycero-phospholipids effectively stimulate the ATPase, including PIP, PIP2, and cardiolipin. Phosphoinositol-containing sphingolipids, major components of the plasma membrane, are also shown to stimulate the ATPase at significantly lower levels than the glycerophospholipids and must also be considered as important effectors in vivo. © 1992.