A novel phosphorylated lipid counteracts activation of the renal plasma membrane (Ca2+ + Mg2+)ATPase by endogenous phosphatidylinositol-4-phosphate.

ABSTRACT

The plasma membrane (Ca2+ + Mg2+)ATPase is activated by acidic phospholipids in reconstituted systems. In this report it is shown that reversible phosphorylation of endogenous phosphatidylinositol regulates the renal plasma membrane (Ca2+ + Mg2+)ATPase, and that a novel phosphorylated lipid that can be isolated from the same membrane strongly counteracts the stimulatory effect of phosphatidylinositol-4-phosphate.