title: Exchange between inorganic phosphate and adenosine triphosphate in (Na+,K+)-ATPase.
abstract: (Na+,K+)-ATPase is able to catalyze a continuous ATP in equilibrium Pi exchange in the presence of Na+ and in the absence of a transmembrane ionic gradient. At pH 7.6 the Na+ concentration required for half-maximal activity is 85 mM and at pH 5.1 it is 340 mM. In the presence of optimal Na+ concentration, the rate of exchange is maximal at pH 6.0 and varies with ADP and Pi concentration in the assay medium. ATP in equilibrium Pi exchange is inhibited by K+ and by ouabain.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008564:Membrane Potentials; D010042:Ouabain / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D012756:Sheep; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D010710:Phosphates; D010042:Ouabain; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D011188:Potassium