Conformation sodium-potassium pump

The stmcture of the sodium-potassium pump was solved in 2007 to a resolution of 3.5 A (Fig. lb), in complex with two bound rubidium ions (13). Structures were also solved for other members of the P-type ATPase family (18, 19) around the same time revealing the structural similarity between family members as well as the conformational changes that occur during function. 

ANIMATED FIGURE 8.25 A mechanism for NaVK+ATPase (the sodium-potassium ion pump). The model assumes two principal conformations, Ej and E2. Binding of Na+ ions to Ej is followed by phosphorylation and release of ADP. Na+ ions are transported and released, and K+ ions are bound before dephosphorylation of the enzyme. Transport and release of K+ ions complete the cycle. Sign in at www.thomsonedu.com/iogin for an animated version of this figure. 

There are at least two conformations of the ion pump proteins.552,5523 In one conformation the protein binds three sodium ions tightly, while in the other conformation it binds two potassium ions. The ATP operates the "motor" that carries out the conformational changes. In Fig. 8-25 the ion pump, in conformation A, is shown embedded in a membrane. 

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