(Na++K+)-ATPase (NKA) comprises two basic alpha and beta subunits: The larger alpha subunit catalyzes the hydrolysis of ATP for active transport of Na+ and K+ ions across the plasma membrane; the smaller beta subunit does not take part in the catalytic process of the enzyme. Little is known about allosteric regulation of the NKA beta subunit. Here, we report a surprising finding that extracellular stimuli on the native beta(1) subunit can generate a significant impact on the catalytic function of NKA. By using a beta(1) subunit-specific monoclonal antibody JY2948, we found that the JY2948-beta(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 beta(1) subunit and uncovers the latent allosteric property of the beta(1) subunit, which remotely controls the NKA catalytic function. (C) 2011 Elsevier Inc. All rights reserved.