Na+, K+-ATPase: relation of conformational transitions to function.

In its native environment, Na+, K+-ATPase of the plasma membrane is an oligomer consisting of two or more of each of two major subunits. Na+ and K+ move across the membrane through the channels that exist between the catalytic subunits of this oligomer. Two distinct ligand-induced conformational transitions (one due to the binding of K+ and ATP to the enzyme, and the other resulting from the phosphorylation of the enzyme in the presence of Na+ and ATP) cause changes in the geometries of the intersubunit channels, and provide the necessary energy-linked gating mechanisms for the transmembrane movements of ions against electrochemical gradients.