Allosteric property of the (Na++K+)-ATPase β1 subunit

Abstract (Na + +K + )-ATPase (NKA) comprises two basic α and β subunits: The larger α subunit catalyzes the hydrolysis of ATP for active transport of Na + and K + ions across the plasma membrane; the smaller β subunit does not take part in the catalytic process of the enzyme. Little is known about allosteric regulation of the NKA β subunit. Here, we report a surprising finding that extracellular stimuli on the native β 1 subunit can generate a significant impact on the catalytic function of NKA. By using a β 1 subunit-specific monoclonal antibody JY2948, we found that the JY2948–β 1 subunit interaction markedly enhances the catalytic activity of the enzyme and increases the apparent affinity of Na + and K + ions for both ouabain-resistant rat NKA and ouabain-sensitive dog NKA. This study provides the first evidence to identify an allosteric binding site residing on the NKA β 1 subunit and uncovers the latent allosteric property of the β 1 subunit, which remotely controls the NKA catalytic function.