Differential effects of lipid depletion on membrane sodium-plus-potassium ion-dependent adenosine triphosphatase and potassium ion-dependent phosphatase.
The phospholipid-dependence of the (Na-++K-+)-dependent ATPase (adenosine triphosphatase) (EC 3.6.1.3) and associated K-+-dependent phosphatase activity (EC 3.6.1.7) have been compared. Unlike the (Na-++K-+)-dependent ATPase activities, the K-+-dependent phosphatase activities of a number of different preparations were not closely correlated with their total phospholipid contents. After partial lipid depletion with a single extraction in Lubrol W the residual ATPase and phosphatase activities were correlated, but their magnitudes were quite different: on average only about 5% of the former remained compared with 50% of the latter. A similar differential effect on these activities was found after extraction with deoxycholate. In contrast with the ATPase, consistent restoration of the phosphatase activity of Lubrol-extracted enzymes by added exogenous phospholipids was not observed. We conclude that, although the K-+-dependent phosphatase may be lipid-dependent, the lipid requirement must be different from that of the complete ATPase system, and this difference should help investigations of their relationship.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002614:Chelating Agents; D003840:Deoxycholic Acid; D003902:Detergents; D007668:Kidney / Q000201:enzymology; D050356:Lipid Metabolism; D008566:Membranes / Q000378:metabolism; D008861:Microsomes / Q000201:enzymology*; D010743:Phospholipids / Q000032:analysis; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012964:Sodium / Q000378:metabolism
D002614:Chelating Agents; D003902:Detergents; D010743:Phospholipids; D003840:Deoxycholic Acid; D012964:Sodium; D010744:Phosphoric Monoester Hydrolases; D000251:Adenosine Triphosphatases; D011188:Potassium