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In biochemistry, an electrogenic transmembrane ATPase common to all cellular life, alternately known as the Na+/K+ pump or Na+/K+ exchanger, helps maintain cell potential and regulate cellular volume; this "sodium-potassium pump" is evolutionarily conserved.

To maintain the cell potential, cells need to keep a low intracellular (within) concentration of sodium ions, and high levels of potassium ions. Outside cells, there is high concentrations of sodium and low concentrations of potassium, so diffusion occurs through ion channels in the cell membrane. To keep the appropriate concentrations the sodium-potassium pump pumps sodium out and potassium in. The mechanism is:

Oubain inhibits pump operation.

The electrical and concentration gradient established by the sodium-potassium ATPase supports not only the cell resting potential but theaction potentials of nerves and muscles. Export of sodium from the cell provides the driving force for several facilitated transporters, which import glucose, amino acids and other nutrients into the cell. Translocation of sodium from one side of an epithelium to the other side creates an osmostic gradient that drives the absorption of water.

See also: active transport