Binding of 1 Rb+ accelerates dephosphorylation of the Na+/K+-ATPase without leading to Rb+ occlusion

S. B. KAUFMAN; R. M. GONZÁLEZ-LEBRERO; P. J. GARRAHAN; R. C. ROSSI

ANN. N. Y. ACADEMY SCIEN.

NYAS

Año: 2003 vol. 986 p. 155 - 158

1749-6632

We have reported that, 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+]. We here provide direct experimental evidence supporting the explanation that the binding of a single Rb+ to the phosphoenzyme conformer E2P accelerates dephosphorylation without leading to the occlusion of the cation.