The interaction of potassium ions and ATP on the sodium pump of resealed red cell ghosts.
1. Ouabain-sensitive K or Rb influx was measure into ghosts resealed to contain ATP concentrations of 1 micrometers-3 mM and no K. 2. Increasing ATP from 1 to 100 micro M, at saturation external K, increased K influx about twentyfold while have no effect on the ratio of ouabain-sensitive K influx to ouabain-sensitive ATPase activity. 3. Increasing external K decreased the apparent affinity for ATP. Similarly increasing ATP decreased the apparent affinity for external K. 4. The K influx can be empirically described as: influx = VmaxK2/(K + Kapp)2. Increasing ATP increased Vmax and (Kapp)2 by the same amount. 5. These results are consistent with a consecutive model for the Na pump in which an ATP-dependent reaction follows a K-activated dephosphorylation.
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D001693:Biological Transport, Active / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D011188:Potassium / Q000097:blood / Q000494:pharmacology*; D012413:Rubidium / Q000097:blood; D012964:Sodium / Q000097:blood*
D000255:Adenosine Triphosphate; D012964:Sodium; D012413:Rubidium; D011188:Potassium