Sodium-potassium ATPase

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Identifiers
EC number	3.6.3.9
CAS number	9001-07-0
Alt. names
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway

Sodium-potassium ATPase (also known as Na⁺/K⁺-ATPase, sodium-potassium pump, and Na⁺/K⁺ pump) is an essential enzyme found in the plasma membrane of all animal cells. It is classified as a P-type ATPase, an enzyme that uses adenosine triphosphate (ATP) to transport ions across cell membranes.

Function

The primary function of sodium-potassium ATPase is to regulate the concentrations of sodium (Na⁺) and potassium (K⁺) ions within the cell. This regulation is crucial for maintaining the cell membrane potential, which is vital for neuronal firing, muscle contraction, and various cellular transport processes.

The enzyme operates by pumping three sodium ions out of the cell and two potassium ions into the cell against their concentration gradients, using energy derived from the hydrolysis of ATP. This activity is critical for maintaining the osmotic balance and electrochemical gradient across the cell membrane.

Structure

Sodium-potassium ATPase is a heteromeric protein complex composed of multiple subunits:

• The α (alpha) subunit – contains the sites for ATP binding and ion transport.
• The β (beta) subunit – essential for proper folding and membrane localization of the alpha subunit.
• The γ (gamma) subunit – a regulatory subunit, which modulates the activity of the pump.

Clinical Significance

Sodium-potassium ATPase plays a significant role in several physiological processes and diseases. It is a target for cardiac glycosides like digoxin and ouabain, which are used in the treatment of heart failure and arrhythmia by increasing the force of heart contraction.

Disruptions in the normal functioning of the Na⁺/K⁺ pump can lead to conditions such as hypertension, epilepsy, and other disorders related to electrolyte imbalance.

Research

Research on sodium-potassium ATPase continues to reveal its implications in various health conditions and its potential as a therapeutic target. Studies have explored its role in neurological disorders, cardiovascular diseases, and its interaction with various hormones and drugs.

See Also

• Cell membrane
• Electrolyte
• Membrane potential
• P-type ATPase