Allosteric interactions in (Na+ + K+)-ATPase

T. Tobin, S. P. Banerjee, A. K. Sen

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


SODIUM and potassium ions are both required to activate the (Na+ + K+)-dependent-ATPase and each inhibits activation by the other1. The K+ activates the turnover of enzyme hyperbolically at low Na+ concentrations, but with increasing concentrations of Na+ the activation curve becomes sigmoid2. Similarly at low concentrations of K+, the Na+ activation curve is hyperbolic but at high concentrations of K+ it becomes sigmoid1. These data indicate the presence of at least two Na+ and/or K+ sites, respectively, but do not indicate the mechanism of interaction between these ions or sites3. Priestland and Whittam2, and others, have suggested that direct competition between the cations for the activating sites can account for the sigmoidal activation curves in the presence of high concentrations of the other cation. Alternatively, Robinson4 has argued that the sigmoidal activation curves, which are consistent with the heterotropic effects of an allosteric activator5, are evidence for allosteric interactions in the (Na+ + K+)-ATPase. In support of this hypothesis he has presented evidence for a co-operativity in the K+ activation of the p-nitrophenyl-phosphatase activity of the (Na+ + K+)-ATPase4. As Garrahan6 has pointed out, however, these data are not conclusive.

Original languageEnglish
Pages (from-to)745-746
Number of pages2
Issue number5234
StatePublished - 1970

ASJC Scopus subject areas

  • General


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