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Na+/K+-ATPase
-ATPase (sodium-potassium adenosine triphosphatase, also known as the pump or sodium-potassium pump) is an enzyme () (an electrogenic transmembrane ATPase) found in the plasma membrane of all animal cells. The -ATPase enzyme is a solute pump that pumps sodium out of cells while pumping potassium into cells, both against their concentration gradients. This pumping is active (it uses energy from ATP) and is important for cell physiology. An example application is nerve conduction.
It has antiporter-like activity but is not actually an antiporter since both molecules are moving against their concentration gradient.
== Sodium-potassium pumps ==
Active transport is responsible for the fact that cells contain a relatively high concentrations of potassium ions but low concentrations of sodium ions. The mechanism responsible for this is the sodium-potassium pump, which moves these two ions in opposite directions across the plasma membrane. This was investigated by following the passage of radioactively labeled ions across the plasma membrane of certain cells. It was found that the concentrations of sodium and potassium ions on the two sides of the membrane are interdependent, suggesting that the same carrier transports both ions. It is now known that the carrier is an ATP-ase and that it pumps three sodium ions out of the cell for every two potassium ions pumped in.
The sodium-potassium pump was discovered in the 1950s by a Danish scientist, Jens Christian Skou, who was awarded a Nobel Prize in 1997. It marked an important step forward in the understanding of how ions get into and out of cells, and it has a particular significance for excitable cells such as nervous cells, which depend on this pump for responding to stimuli and transmitting impulses.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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