title: Potassium ion-stimulated and sodium ion-dependent adenosine diphosphate-adenosine triphosphate exchange activity in a kidney microsomal fraction.
abstract: 1. K(+) did not affect the Mg(2+)-dependent transphosphorylation but markedly increased the Na(+)-stimulated ADP-ATP exchange rate mediated by a microsomal fraction from guinea-pig kidney. 2. Rb(+), Cs(+), NH(4) (+) and Li(+) were equally effective in stimulating the Na(+)-dependent ADP-ATP exchange activity. 3. Treatment of the microsomal fraction with N-ethylmaleimide or increased concentrations of Mg(2+) prevented stimulation of the Na(+)-dependent exchange reaction by K(+). 4. Ouabain (2.5mum) inhibited ATP hydrolysis by 33% but did not decrease the K(+)-stimulated Na(+)-dependent ADP-ATP exchange rate. 5. A possible mechanism for stimulation of exchange activity by K(+) is discussed.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002586:Cesium / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D006168:Guinea Pigs; D006868:Hydrolysis; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism*; D008094:Lithium / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012413:Rubidium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology
chemical_list: D000644:Quaternary Ammonium Compounds; D002586:Cesium; D010042:Ouabain; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D008094:Lithium; D012964:Sodium; D008274:Magnesium; D012413:Rubidium; D005033:Ethylmaleimide; D011188:Potassium