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.