| Modification Notes |
The ubiquitously expressed sodium/potassium-ATPase (Na+/K+-ATPase) exists as a oligomeric plasma membrane complex that couples the hydrolysis of one molecule of ATP to the importation of three Na+ ions and two K+ ions against their respective electrochemical gradients. As a member of the P-type family of ion motives, Na+/K+-ATPase plays a critical role in maintaining cellular volume, resting membrane potential and Na+-coupled solute transport. Multiple isoforms of three subunits, å, ∫ and ©, comprise the Na+/K+-ATPase oligomer. The å subunit contains the binding sites for ATP and the cations; the glycosylated ∫ subunit ensures correct folding and membrane insertion of the å subunits. The small © subunit co-localizes with the å subunit in nephron segments, where it increases the affinity of Na+/K+-ATPase for ATP. The ∫ subunit, but not the © subunit, is essential for normal activity of Na+/K+-ATPase. The å subunit is subject to phosphorylation in select serine residues. |