ATP1B1B3

ATP1B1B3 is not a formally recognized single gene; it is an informal reference that may be used to denote the beta subunits of the Na+/K+-ATPase encoded by ATP1B1 and ATP1B3. The two genes produce distinct beta subunits that assemble with alpha subunits to form functional Na+/K+-ATPase enzymes.

The Na+/K+-ATPase is a membrane-bound enzyme composed of a catalytic alpha subunit and one or more beta subunits. The beta subunits are single-pass transmembrane proteins that assist in proper folding, maturation, and trafficking of the complex to the plasma membrane. They influence protein stability, subcellular localization, and, in some cases, the kinetic properties and ion affinities of the pump, contributing to isoform-specific activity.

Functionally, the Na+/K+-ATPase uses energy from ATP hydrolysis to exchange three intracellular Na+ ions for two extracellular K+ ions. This activity maintains essential electrochemical gradients across the cell membrane, which drive nerve impulse transmission, muscle contraction, secondary active transport, and maintenance of cell volume.

Expression and regulation of the beta subunits show tissue specificity. ATP1B1 (beta-1) is broadly expressed, while ATP1B3 (beta-3) displays more restricted patterns that can vary by tissue and developmental stage. Subunit composition can affect pump localization, interaction with cofactors, and responses to hormonal and signaling cues.

Clinical and research relevance lies in the sensitivity of Na+/K+-ATPase function to subunit composition. Altered expression or mutations affecting the beta subunits can disrupt pump assembly and trafficking, with potential implications for neurological physiology and related disorders. The beta subunits are common subjects in studies of pump regulation and membrane biology.