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Sodium and potassium competition in potassium-selective and non-selective channels

Author

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  • David B. Sauer

    (University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9040, USA
    Present address: The Helen L and Martin S Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, New York University School of Medicine, 540 First Avenue, New York, New York 10016, USA)

  • Weizhong Zeng

    (University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9040, USA
    Howard Hughes Medical Institute, University of Texas Southwestern Medical Center)

  • John Canty

    (University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9040, USA
    Present address: Duke University, Durham, North Carolina 27708, USA)

  • Yeeling Lam

    (University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9040, USA)

  • Youxing Jiang

    (University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9040, USA
    Howard Hughes Medical Institute, University of Texas Southwestern Medical Center)

Abstract

Potassium channels selectively conduct K+, primarily to the exclusion of Na+, despite the fact that both ions can bind within the selectivity filter. Here we perform crystallographic titration and single-channel electrophysiology to examine the competition of Na+ and K+ binding within the filter of two NaK channel mutants; one is the potassium-selective NaK2K mutant and the other is the non-selective NaK2CNG, a CNG channel pore mimic. With high-resolution structures of these engineered NaK channel constructs, we explicitly describe the changes in K+ occupancy within the filter upon Na+ competition by anomalous diffraction. Our results demonstrate that the non-selective NaK2CNG still retains a K+-selective site at equilibrium, whereas the NaK2K channel filter maintains two high-affinity K+ sites. A double-barrier mechanism is proposed to explain K+ channel selectivity at low K+ concentrations.

Suggested Citation

  • David B. Sauer & Weizhong Zeng & John Canty & Yeeling Lam & Youxing Jiang, 2013. "Sodium and potassium competition in potassium-selective and non-selective channels," Nature Communications, Nature, vol. 4(1), pages 1-9, December.
    • Handle: RePEc:nat:natcom:v:4:y:2013:i:1:d:10.1038_ncomms3721
    DOI: 10.1038/ncomms3721
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    Cited by:

    1. Marcos Matamoros & Xue Wen Ng & Joshua B. Brettmann & David W. Piston & Colin G. Nichols, 2023. "Conformational plasticity of NaK2K and TREK2 potassium channel selectivity filters," Nature Communications, Nature, vol. 14(1), pages 1-12, December.

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