Skip to main content
NCBI home page
Biophysical Journal logoLink to Biophysical Journal
. 1993 Nov;65(5):2089–2096. doi: 10.1016/S0006-3495(93)81244-X

Conduction properties of the cloned Shaker K+ channel.

L Heginbotham 1, R MacKinnon 1
PMCID: PMC1225944  PMID: 8298038

Abstract

The conduction properties of the cloned Shaker K+ channel were studied using electrophysiological techniques. Single channel conductance increases in a sublinear manner with symmetric increases in K+ activity, reaching saturation by 0.6 M K+. The Shaker K+ channel is highly selective among monovalent cations; under bi-ionic conditions, its selectivity sequence is K+ > Rb+ > NH+4 > Cs+ > Na+, whereas, by relative conductance in symmetric solutions, it is K+ > NH+4 > Rb+ > Cs+. In Cs+ solutions, single channel currents were too small to be measured directly, so nonstationary fluctuation analysis was used to determine the unitary Cs+ conductance. The single channel conductance displays an anomalous molefraction effect in symmetric mixtures of K+ and NH+4, suggesting that the conducting pore is occupied by multiple ions simultaneously.

Full text

PDF
2089

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Adelman J. P., Shen K. Z., Kavanaugh M. P., Warren R. A., Wu Y. N., Lagrutta A., Bond C. T., North R. A. Calcium-activated potassium channels expressed from cloned complementary DNAs. Neuron. 1992 Aug;9(2):209–216. doi: 10.1016/0896-6273(92)90160-f. [DOI] [PubMed] [Google Scholar]
  2. Atkinson N. S., Robertson G. A., Ganetzky B. A component of calcium-activated potassium channels encoded by the Drosophila slo locus. Science. 1991 Aug 2;253(5019):551–555. doi: 10.1126/science.1857984. [DOI] [PubMed] [Google Scholar]
  3. Begenisich T., De Weer P. Potassium flux ratio in voltage-clamped squid giant axons. J Gen Physiol. 1980 Jul;76(1):83–98. doi: 10.1085/jgp.76.1.83. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Blatz A. L., Magleby K. L. Ion conductance and selectivity of single calcium-activated potassium channels in cultured rat muscle. J Gen Physiol. 1984 Jul;84(1):1–23. doi: 10.1085/jgp.84.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Butler A., Tsunoda S., McCobb D. P., Wei A., Salkoff L. mSlo, a complex mouse gene encoding "maxi" calcium-activated potassium channels. Science. 1993 Jul 9;261(5118):221–224. doi: 10.1126/science.7687074. [DOI] [PubMed] [Google Scholar]
  6. Cecchi X., Wolff D., Alvarez O., Latorre R. Mechanisms of Cs+ blockade in a Ca2+-activated K+ channel from smooth muscle. Biophys J. 1987 Nov;52(5):707–716. doi: 10.1016/S0006-3495(87)83265-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Coronado R., Rosenberg R. L., Miller C. Ionic selectivity, saturation, and block in a K+-selective channel from sarcoplasmic reticulum. J Gen Physiol. 1980 Oct;76(4):425–446. doi: 10.1085/jgp.76.4.425. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Eisenman G., Latorre R., Miller C. Multi-ion conduction and selectivity in the high-conductance Ca++-activated K+ channel from skeletal muscle. Biophys J. 1986 Dec;50(6):1025–1034. doi: 10.1016/S0006-3495(86)83546-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Goldman D. E. POTENTIAL, IMPEDANCE, AND RECTIFICATION IN MEMBRANES. J Gen Physiol. 1943 Sep 20;27(1):37–60. doi: 10.1085/jgp.27.1.37. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. HODGKIN A. L., KATZ B. The effect of sodium ions on the electrical activity of giant axon of the squid. J Physiol. 1949 Mar 1;108(1):37–77. doi: 10.1113/jphysiol.1949.sp004310. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. HODGKIN A. L., KEYNES R. D. The potassium permeability of a giant nerve fibre. J Physiol. 1955 Apr 28;128(1):61–88. doi: 10.1113/jphysiol.1955.sp005291. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Hagiwara S., Miyazaki S., Krasne S., Ciani S. Anomalous permeabilities of the egg cell membrane of a starfish in K+-Tl+ mixtures. J Gen Physiol. 1977 Sep;70(3):269–281. doi: 10.1085/jgp.70.3.269. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hille B. Potassium channels in myelinated nerve. Selective permeability to small cations. J Gen Physiol. 1973 Jun;61(6):669–686. doi: 10.1085/jgp.61.6.669. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Hladky S. B., Haydon D. A. Ion transfer across lipid membranes in the presence of gramicidin A. I. Studies of the unit conductance channel. Biochim Biophys Acta. 1972 Aug 9;274(2):294–312. doi: 10.1016/0005-2736(72)90178-2. [DOI] [PubMed] [Google Scholar]
  15. Hoshi T., Zagotta W. N., Aldrich R. W. Biophysical and molecular mechanisms of Shaker potassium channel inactivation. Science. 1990 Oct 26;250(4980):533–538. doi: 10.1126/science.2122519. [DOI] [PubMed] [Google Scholar]
  16. MacKinnon R., Yellen G. Mutations affecting TEA blockade and ion permeation in voltage-activated K+ channels. Science. 1990 Oct 12;250(4978):276–279. doi: 10.1126/science.2218530. [DOI] [PubMed] [Google Scholar]
  17. Neyton J., Miller C. Discrete Ba2+ block as a probe of ion occupancy and pore structure in the high-conductance Ca2+ -activated K+ channel. J Gen Physiol. 1988 Nov;92(5):569–586. doi: 10.1085/jgp.92.5.569. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Neyton J., Miller C. Potassium blocks barium permeation through a calcium-activated potassium channel. J Gen Physiol. 1988 Nov;92(5):549–567. doi: 10.1085/jgp.92.5.549. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Reuter H., Stevens C. F. Ion conductance and ion selectivity of potassium channels in snail neurones. J Membr Biol. 1980 Dec 15;57(2):103–118. doi: 10.1007/BF01868997. [DOI] [PubMed] [Google Scholar]
  20. Schoppa N. E., McCormack K., Tanouye M. A., Sigworth F. J. The size of gating charge in wild-type and mutant Shaker potassium channels. Science. 1992 Mar 27;255(5052):1712–1715. doi: 10.1126/science.1553560. [DOI] [PubMed] [Google Scholar]
  21. Shapiro M. S., DeCoursey T. E. Selectivity and gating of the type L potassium channel in mouse lymphocytes. J Gen Physiol. 1991 Jun;97(6):1227–1250. doi: 10.1085/jgp.97.6.1227. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Sigworth F. J. The variance of sodium current fluctuations at the node of Ranvier. J Physiol. 1980 Oct;307:97–129. doi: 10.1113/jphysiol.1980.sp013426. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Vestergaard-Bogind B., Stampe P., Christophersen P. Single-file diffusion through the Ca2+-activated K+ channel of human red cells. J Membr Biol. 1985;88(1):67–75. doi: 10.1007/BF01871214. [DOI] [PubMed] [Google Scholar]
  24. Wagoner P. K., Oxford G. S. Cation permeation through the voltage-dependent potassium channel in the squid axon. Characteristics and mechanisms. J Gen Physiol. 1987 Aug;90(2):261–290. doi: 10.1085/jgp.90.2.261. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Yellen G., Jurman M. E., Abramson T., MacKinnon R. Mutations affecting internal TEA blockade identify the probable pore-forming region of a K+ channel. Science. 1991 Feb 22;251(4996):939–942. doi: 10.1126/science.2000494. [DOI] [PubMed] [Google Scholar]
  26. Yellen G. Relief of Na+ block of Ca2+-activated K+ channels by external cations. J Gen Physiol. 1984 Aug;84(2):187–199. doi: 10.1085/jgp.84.2.187. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Biophysical Journal are provided here courtesy of The Biophysical Society

RESOURCES