Figure 1: Post-Albers diagram of the Na⁺/K⁺ transport cycle.

In this simplified scheme, E₁ conformations represent those in which binding sites may be accessed from the intracellular side. In these states, two K⁺ (orange balls) are released, three Na⁺ (green balls) are bound and occluded, and the protein is phosphorylated. In P-E₂ conformations, the binding sites become accessible from the external environment, and the three Na⁺ are released, two K⁺ are bound and occluded, and the protein autodephosphorylates. The states enclosed by the dotted box were isolated by removal of K⁺ from all solutions and by the presence of 5 mM MgATP (and of ADP scavengers)^8,14 in the internal solution.