title: Specific sodium-22 binding to a purified sodium + potassium adenosine triphosphatase. Inhibition by ouabain.
abstract: Analysis of sodium-22 binding to purified sodium + potassium ion-activated adenosine triphosphatase (Na+, K+)-ATPase reveals the presence of two classes of binding sites. The higher affinity site (Kd = 0.2 mM) binds 6 to 7 nmol of sodium per mg of protein. Pretreatment of (Na+, K+)-ATPase with ouabain blocks the binding of sodium to this higher affinity site. Neither heat-denatured enzyme nor phospholipids extracted from the (Na+, K+)-ATPase contain a ouabain-inhibitable, higher affinity sodium binding site. The ouabain enzyme complex therefore appears to contain altered binding sites for cations.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002794:Choline / Q000494:pharmacology; D004789:Enzyme Activation; D007679:Kidney Medulla / Q000201:enzymology; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology*; D011485:Protein Binding; D012756:Sheep; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology*; D012975:Sodium Isotopes
chemical_list: D012975:Sodium Isotopes; D010042:Ouabain; D012964:Sodium; D000251:Adenosine Triphosphatases; D002794:Choline; D011188:Potassium