Transcription factors regulating the Na+/K+-ATPase genes

Na+/K+-ATPase is composed of two subunits named α and β. Each subunit has three isoforms of α1, α2 and α3 for α, β1, β2 and β3 for β (4,11,18,25). Expression of each isoform gene is regulated tissue specifically and developmentally (5,20,21). Each isoform has its unique affinities for ligands including Na+, K+ and ATP and for an inhibitor ouabain (6,9,10). It is believed that any of the α isoforms could be assembled with any of the β isoforms, suggesting that the gene expression of each isoform gene is involved in the production of functional difference of the assembled enzyme. Each isoform gene has been isolated from various species and characterized (12,15,17,26,27, 28,30,32).