Binding of 1 Rb+ accelerates dephosphorylation of the Na+,K+-ATPase without leading to Rb+ occlusion.
In steady-state conditions and for concentrations of the K(+)-congener Rb(+) less than 2.5 mM, Rb(+)-dependent ATPase activity is significantly higher than the steady-state rate of breakdown of Rb(+)-occluded states, a discrepancy that disappears at sufficiently high [Rb(+)]. Direct experimental evidence is provided that supports the explanation that the binding of a single Rb(+) to the phosphoenzyme conformer E(2)P accelerates dephosphorylation without leading to the occlusion of the cation.
Kaufman
Sergio B
SB
Instituto de Química y Fisicoquímica Biológicas and Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Argentina. sbkauf@qb.ffyb.uba.ar
González-Lebrero
Rodolfo M
RM
Garrahan
Patricio J
PJ
Rossi
Rolando C
RC
D000818:Animals; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D010766:Phosphorylation; D012413:Rubidium / Q000493:pharmacokinetics* / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013552:Swine
D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium