Transient behaviour of the Na+/K+-pump: microscopic analysis of nonstationary ion-translocation.
In recent years fast perturbation techniques have been applied for investigating the mechanism of the Na+/K+-pump. Experiments in which nonstationary pump-currents and ion fluxes are measured after a voltage or ATP-concentration jump yield kinetic information which cannot be obtained from ordinary steady-state experiments. In this paper a theoretical treatment is described by which transient pump-currents and ion fluxes can be analyzed in a unified way. The method is based on the assumption that the operation of the pump involves a sequence of conformational transitions and ion-binding and -release steps. The charge displacements associated with the individual reaction steps are described by a set of dielectric coefficients. The nonstationary behaviour of the Na+/K+-pump is analyzed on the basis of the Albers-Post reaction cycle. It is shown that the different studies of transient pump-currents and ion fluxes carried out so far lead to internally consistent conclusions with respect to the nature of the electrogenic steps of the transport cycle.
Läuger
P
P
Department of Biology, University of Konstanz, F.R.G.
Apell
H J
HJ
D000255:Adenosine Triphosphate / Q000378:metabolism; D001693:Biological Transport, Active; D004553:Electric Conductivity; D066298:In Vitro Techniques; D007700:Kinetics; D008051:Lipid Bilayers; D008564:Membrane Potentials; D008962:Models, Theoretical; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D008051:Lipid Bilayers; D000255:Adenosine Triphosphate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium