Skip to main content
NCBI home page
Biophysical Journal logoLink to Biophysical Journal
. 2000 Nov;79(5):2475–2493. doi: 10.1016/S0006-3495(00)76490-3

The interaction of Na(+) and K(+) in the pore of cyclic nucleotide-gated channels.

K Gamel 1, V Torre 1
PMCID: PMC1301132  PMID: 11053124

Abstract

The permeability ratio between K(+) and Na(+) ions in cyclic nucleotide-gated channels is close to 1, and the single channel conductance has almost the same value in the presence of K(+) or Na(+). Therefore, K(+) and Na(+) ions are thought to permeate with identical properties. In the alpha-subunit from bovine rods there is a loop of three prolines at positions 365 to 367. When proline 365 is mutated to a threonine, a cysteine, or an alanine, mutant channels exhibit a complex interaction between K(+) and Na(+) ions. Indeed K(+), Rb(+) and Cs(+) ions do not carry any significant macroscopic current through mutant channels P365T, P365C and P365A and block the current carried by Na(+) ions. Moreover in mutant P365T the presence of K(+) in the intracellular (or extracellular) medium caused the appearance of a large transient inward (or outward) current carried by Na(+) when the voltage command was quickly stepped to large negative (or positive) membrane voltages. This transient current is caused by a transient potentiation, i.e., an increase of the open probability. The permeation of organic cations through these mutant channels is almost identical to that through the wild type (w.t.) channel. Also in the w.t. channel a similar but smaller transient current is observed, associated to a slowing down of the channel gating evident when intracellular Na(+) is replaced with K(+). As a consequence, a rather simple mechanism can explain the complex behavior here described: when a K(+) ion is occupying the pore there is a profound blockage of the channel and a potentiation of gating immediately after the K(+) ion is driven out. Potentiation occurs because K(+) ions slow down the rate constant K(off) controlling channel closure. These results indicate that K(+) and Na(+) ions do not permeate through CNG channels in the same way and that K(+) ions influence the channel gating.

Full Text

The Full Text of this article is available as a PDF (774.8 KB).

Selected References

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

  1. Adzhubei A. A., Sternberg M. J. Left-handed polyproline II helices commonly occur in globular proteins. J Mol Biol. 1993 Jan 20;229(2):472–493. doi: 10.1006/jmbi.1993.1047. [DOI] [PubMed] [Google Scholar]
  2. Becchetti A., Gamel K., Torre V. Cyclic nucleotide-gated channels. Pore topology studied through the accessibility of reporter cysteines. J Gen Physiol. 1999 Sep;114(3):377–392. doi: 10.1085/jgp.114.3.377. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Biel M., Zong X., Hofmann F. Molecular diversity of cyclic nucleotide-gated cation channels. Naunyn Schmiedebergs Arch Pharmacol. 1995 Dec;353(1):1–10. doi: 10.1007/BF00168909. [DOI] [PubMed] [Google Scholar]
  4. Catterall W. A. Molecular properties of a superfamily of plasma-membrane cation channels. Curr Opin Cell Biol. 1994 Aug;6(4):607–615. doi: 10.1016/0955-0674(94)90083-3. [DOI] [PubMed] [Google Scholar]
  5. Doyle D. A., Morais Cabral J., Pfuetzner R. A., Kuo A., Gulbis J. M., Cohen S. L., Chait B. T., MacKinnon R. The structure of the potassium channel: molecular basis of K+ conduction and selectivity. Science. 1998 Apr 3;280(5360):69–77. doi: 10.1126/science.280.5360.69. [DOI] [PubMed] [Google Scholar]
  6. Eismann E., Müller F., Heinemann S. H., Kaupp U. B. A single negative charge within the pore region of a cGMP-gated channel controls rectification, Ca2+ blockage, and ionic selectivity. Proc Natl Acad Sci U S A. 1994 Feb 1;91(3):1109–1113. doi: 10.1073/pnas.91.3.1109. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Finn J. T., Grunwald M. E., Yau K. W. Cyclic nucleotide-gated ion channels: an extended family with diverse functions. Annu Rev Physiol. 1996;58:395–426. doi: 10.1146/annurev.ph.58.030196.002143. [DOI] [PubMed] [Google Scholar]
  8. Gordon S. E., Zagotta W. N. Localization of regions affecting an allosteric transition in cyclic nucleotide-activated channels. Neuron. 1995 Apr;14(4):857–864. doi: 10.1016/0896-6273(95)90229-5. [DOI] [PubMed] [Google Scholar]
  9. Gordon S. E., Zagotta W. N. Subunit interactions in coordination of Ni2+ in cyclic nucleotide-gated channels. Proc Natl Acad Sci U S A. 1995 Oct 24;92(22):10222–10226. doi: 10.1073/pnas.92.22.10222. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Goulding E. H., Tibbs G. R., Liu D., Siegelbaum S. A. Role of H5 domain in determining pore diameter and ion permeation through cyclic nucleotide-gated channels. Nature. 1993 Jul 1;364(6432):61–64. doi: 10.1038/364061a0. [DOI] [PubMed] [Google Scholar]
  11. Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
  12. Heginbotham L., Abramson T., MacKinnon R. A functional connection between the pores of distantly related ion channels as revealed by mutant K+ channels. Science. 1992 Nov 13;258(5085):1152–1155. doi: 10.1126/science.1279807. [DOI] [PubMed] [Google Scholar]
  13. Jan L. Y., Jan Y. N. A superfamily of ion channels. Nature. 1990 Jun 21;345(6277):672–672. doi: 10.1038/345672a0. [DOI] [PubMed] [Google Scholar]
  14. Jan L. Y., Jan Y. N. Tracing the roots of ion channels. Cell. 1992 May 29;69(5):715–718. doi: 10.1016/0092-8674(92)90280-p. [DOI] [PubMed] [Google Scholar]
  15. Karpen J. W., Zimmerman A. L., Stryer L., Baylor D. A. Gating kinetics of the cyclic-GMP-activated channel of retinal rods: flash photolysis and voltage-jump studies. Proc Natl Acad Sci U S A. 1988 Feb;85(4):1287–1291. doi: 10.1073/pnas.85.4.1287. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Kaupp U. B. Family of cyclic nucleotide gated ion channels. Curr Opin Neurobiol. 1995 Aug;5(4):434–442. doi: 10.1016/0959-4388(95)80002-6. [DOI] [PubMed] [Google Scholar]
  17. Kaupp U. B., Niidome T., Tanabe T., Terada S., Bönigk W., Stühmer W., Cook N. J., Kangawa K., Matsuo H., Hirose T. Primary structure and functional expression from complementary DNA of the rod photoreceptor cyclic GMP-gated channel. Nature. 1989 Dec 14;342(6251):762–766. doi: 10.1038/342762a0. [DOI] [PubMed] [Google Scholar]
  18. Laio A., Torre V. Physical origin of selectivity in ionic channels of biological membranes. Biophys J. 1999 Jan;76(1 Pt 1):129–148. doi: 10.1016/S0006-3495(99)77184-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Li J., Zagotta W. N., Lester H. A. Cyclic nucleotide-gated channels: structural basis of ligand efficacy and allosteric modulation. Q Rev Biophys. 1997 May;30(2):177–193. doi: 10.1017/s0033583597003326. [DOI] [PubMed] [Google Scholar]
  20. Liu D. T., Tibbs G. R., Paoletti P., Siegelbaum S. A. Constraining ligand-binding site stoichiometry suggests that a cyclic nucleotide-gated channel is composed of two functional dimers. Neuron. 1998 Jul;21(1):235–248. doi: 10.1016/s0896-6273(00)80530-9. [DOI] [PubMed] [Google Scholar]
  21. Liu D. T., Tibbs G. R., Siegelbaum S. A. Subunit stoichiometry of cyclic nucleotide-gated channels and effects of subunit order on channel function. Neuron. 1996 May;16(5):983–990. doi: 10.1016/s0896-6273(00)80121-x. [DOI] [PubMed] [Google Scholar]
  22. Menini A. Currents carried by monovalent cations through cyclic GMP-activated channels in excised patches from salamander rods. J Physiol. 1990 May;424:167–185. doi: 10.1113/jphysiol.1990.sp018061. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Menini A. Cyclic nucleotide-gated channels in visual and olfactory transduction. Biophys Chem. 1995 Aug;55(3):185–196. doi: 10.1016/0301-4622(94)00153-b. [DOI] [PubMed] [Google Scholar]
  24. Nizzari M., Sesti F., Giraudo M. T., Virginio C., Cattaneo A., Torre V. Single-channel properties of cloned cGMP-activated channels from retinal rods. Proc Biol Sci. 1993 Oct 22;254(1339):69–74. doi: 10.1098/rspb.1993.0128. [DOI] [PubMed] [Google Scholar]
  25. Park C. S., MacKinnon R. Divalent cation selectivity in a cyclic nucleotide-gated ion channel. Biochemistry. 1995 Oct 17;34(41):13328–13333. doi: 10.1021/bi00041a008. [DOI] [PubMed] [Google Scholar]
  26. Picco C., Menini A. The permeability of the cGMP-activated channel to organic cations in retinal rods of the tiger salamander. J Physiol. 1993 Jan;460:741–758. doi: 10.1113/jphysiol.1993.sp019497. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Root M. J., MacKinnon R. Identification of an external divalent cation-binding site in the pore of a cGMP-activated channel. Neuron. 1993 Sep;11(3):459–466. doi: 10.1016/0896-6273(93)90150-p. [DOI] [PubMed] [Google Scholar]
  28. Ruiz M., Karpen J. W. Opening mechanism of a cyclic nucleotide-gated channel based on analysis of single channels locked in each liganded state. J Gen Physiol. 1999 Jun;113(6):873–895. doi: 10.1085/jgp.113.6.873. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Sesti F., Eismann E., Kaupp U. B., Nizzari M., Torre V. The multi-ion nature of the cGMP-gated channel from vertebrate rods. J Physiol. 1995 Aug 15;487(1):17–36. doi: 10.1113/jphysiol.1995.sp020858. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Sesti F., Nizzari M., Torre V. Effect of changing temperature on the ionic permeation through the cyclic GMP-gated channel from vertebrate photoreceptors. Biophys J. 1996 Jun;70(6):2616–2639. doi: 10.1016/S0006-3495(96)79832-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Sunderman E. R., Zagotta W. N. Mechanism of allosteric modulation of rod cyclic nucleotide-gated channels. J Gen Physiol. 1999 May;113(5):601–620. doi: 10.1085/jgp.113.5.601. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Tibbs G. R., Goulding E. H., Siegelbaum S. A. Allosteric activation and tuning of ligand efficacy in cyclic-nucleotide-gated channels. Nature. 1997 Apr 10;386(6625):612–615. doi: 10.1038/386612a0. [DOI] [PubMed] [Google Scholar]
  33. Varnum M. D., Zagotta W. N. Interdomain interactions underlying activation of cyclic nucleotide-gated channels. Science. 1997 Oct 3;278(5335):110–113. doi: 10.1126/science.278.5335.110. [DOI] [PubMed] [Google Scholar]
  34. Varnum M. D., Zagotta W. N. Subunit interactions in the activation of cyclic nucleotide-gated ion channels. Biophys J. 1996 Jun;70(6):2667–2679. doi: 10.1016/S0006-3495(96)79836-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Zagotta W. N. Molecular mechanisms of cyclic nucleotide-gated channels. J Bioenerg Biomembr. 1996 Jun;28(3):269–278. doi: 10.1007/BF02110700. [DOI] [PubMed] [Google Scholar]
  36. Zagotta W. N., Siegelbaum S. A. Structure and function of cyclic nucleotide-gated channels. Annu Rev Neurosci. 1996;19:235–263. doi: 10.1146/annurev.ne.19.030196.001315. [DOI] [PubMed] [Google Scholar]
  37. Zimmerman A. L. Cyclic nucleotide gated channels. Curr Opin Neurobiol. 1995 Jun;5(3):296–303. doi: 10.1016/0959-4388(95)80041-7. [DOI] [PubMed] [Google Scholar]

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

RESOURCES