Na+/K+-ATPase: Regulation of K+ Access Channels by K+

  • W.-H. Huang
  • A. Askari


Based on studies with the purified canine kidney enzyme (1), we concluded recently that Rb+ (or K+) occlusion sites of the unphosphorylated E2 state of the enzyme are confined within the protein matrix and connected to the medium by narrow and heterogeneous access channels, and that channel heterogeneity is distinct from any differences that may exist among the affinities of the occluded sites that are deep within these channels. More importantly, the same studies indicated that regulation of these channels is also distinct from the regulation of the events at the occluded sites, and identified allosteric regulatory effects of ATP, Na+, and Rb+ on the “width” of the access channels. Here, we present further findings on the interactive allosteric effects of ATP and Rb+ (or K+) on these channels. All experiments were done at 4±C by methods and procedures described before (1).


Access Channel Allosteric Regulation United States Public Health Internal Site Complete Dissociation 
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  1. 1.
    Hasenauer J, Huang W.-H, Askari A (1993) Allosteric regulation of the access channels to the Rb+ occlusion sites of (Na++K+)-ATPase. J Biol. Chem 268: 3289–3297PubMedGoogle Scholar
  2. 2.
    Kapakos JG, Steinberg M (1986) Ligand binding to (NaK)-ATPase labeled with 5-iodoacetamidofluorescein. J Biol Chem 261: 2084–2089PubMedGoogle Scholar
  3. 3.
    Skou JC, Esmann M (1983) The effects of Na+ and K+ on the conformational transitions of (Na++K+)-ATPase. Biochim Biophys Acta 746: 101–113PubMedCrossRefGoogle Scholar

Copyright information

© Dietrich Steinkopff Verlag GmbH & Co. KG, Darmstadt 1994

Authors and Affiliations

  • W.-H. Huang
    • 1
  • A. Askari
    • 1
  1. 1.Department of PharmacologyMedical College of OhioToledoUSA

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