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 E2P accelerates dephosphorylation without leading to the occlusion of the cation.
dephosphorylation occlusion kinetics