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

David B. Sauer, Weizhong Zeng, John Canty, Yeeling Lam, Youxing Jiang

Research output: Contribution to journalArticle

30 Citations (Scopus)

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.

Original languageEnglish (US)
Article number2721
JournalNature Communications
Volume4
DOIs
StatePublished - 2013

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Electrophysiology
Potassium Channels
potassium
Potassium
Sodium
sodium
Ions
Titration
filters
Diffraction
selectivity
electrophysiology
exclusion
titration
affinity
porosity
high resolution
diffraction
ions

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Chemistry(all)
  • Physics and Astronomy(all)

Cite this

Sodium and potassium competition in potassium-selective and non-selective channels. / Sauer, David B.; Zeng, Weizhong; Canty, John; Lam, Yeeling; Jiang, Youxing.

In: Nature Communications, Vol. 4, 2721, 2013.

Research output: Contribution to journalArticle

Sauer, David B. ; Zeng, Weizhong ; Canty, John ; Lam, Yeeling ; Jiang, Youxing. / Sodium and potassium competition in potassium-selective and non-selective channels. In: Nature Communications. 2013 ; Vol. 4.
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