Skip to main content
PMC home page
Biophysical Journal logoLink to Biophysical Journal
. 2000 May;78(5):2334–2348. doi: 10.1016/S0006-3495(00)76779-8

The kinetic and physical basis of K(ATP) channel gating: toward a unified molecular understanding.

D Enkvetchakul 1, G Loussouarn 1, E Makhina 1, S L Shyng 1, C G Nichols 1
PMCID: PMC1300824  PMID: 10777731

Abstract

K(ATP) channels can be formed from Kir6.2 subunits with or without SUR1. The open-state stability of K(ATP) channels can be increased or reduced by mutations throughout the Kir6.2 subunit, and is increased by application of PIP(2) to the cytoplasmic membrane. Increase of open-state stability is manifested as an increase in the channel open probability in the absence of ATP (Po(zero)) and a correlated decrease in sensitivity to inhibition by ATP. Single channel lifetime analyses were performed on wild-type and I154C mutant channels expressed with, and without, SUR1. Channel kinetics include a single, invariant, open duration; an invariant, brief, closed duration; and longer closed events consisting of a "mixture of exponentials," which are prolonged in ATP and shortened after PIP(2) treatment. The steady-state and kinetic data cannot be accounted for by assuming that ATP binds to the channel and causes a gate to close. Rather, we show that they can be explained by models that assume the following regarding the gating behavior: 1) the channel undergoes ATP-insensitive transitions from the open state to a short closed state (C(f)) and to a longer-lived closed state (C(0)); 2) the C(0) state is destabilized in the presence of SUR1; and 3) ATP can access this C(0) state, stabilizing it and thereby inhibiting macroscopic currents. The effect of PIP(2) and mutations that stabilize the open state is then to shift the equilibrium of the "critical transition" from the open state to the ATP-accessible C(0) state toward the O state, reducing accessibility of the C(0) state, and hence reducing ATP sensitivity.

Full Text

The Full Text of this article is available as a PDF (310.3 KB).

Selected References

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

  1. Aguilar-Bryan L., Nichols C. G., Wechsler S. W., Clement J. P., 4th, Boyd A. E., 3rd, González G., Herrera-Sosa H., Nguy K., Bryan J., Nelson D. A. Cloning of the beta cell high-affinity sulfonylurea receptor: a regulator of insulin secretion. Science. 1995 Apr 21;268(5209):423–426. doi: 10.1126/science.7716547. [DOI] [PubMed] [Google Scholar]
  2. Alekseev A. E., Brady P. A., Terzic A. Ligand-insensitive state of cardiac ATP-sensitive K+ channels. Basis for channel opening. J Gen Physiol. 1998 Feb;111(2):381–394. doi: 10.1085/jgp.111.2.381. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Alekseev A. E., Kennedy M. E., Navarro B., Terzic A. Burst kinetics of co-expressed Kir6.2/SUR1 clones: comparison of recombinant with native ATP-sensitive K+ channel behavior. J Membr Biol. 1997 Sep 15;159(2):161–168. doi: 10.1007/s002329900279. [DOI] [PubMed] [Google Scholar]
  4. Ashcroft F. M. Adenosine 5'-triphosphate-sensitive potassium channels. Annu Rev Neurosci. 1988;11:97–118. doi: 10.1146/annurev.ne.11.030188.000525. [DOI] [PubMed] [Google Scholar]
  5. Ashcroft F. M., Gribble F. M. Correlating structure and function in ATP-sensitive K+ channels. Trends Neurosci. 1998 Jul;21(7):288–294. doi: 10.1016/s0166-2236(98)01225-9. [DOI] [PubMed] [Google Scholar]
  6. Baukrowitz T., Schulte U., Oliver D., Herlitze S., Krauter T., Tucker S. J., Ruppersberg J. P., Fakler B. PIP2 and PIP as determinants for ATP inhibition of KATP channels. Science. 1998 Nov 6;282(5391):1141–1144. doi: 10.1126/science.282.5391.1141. [DOI] [PubMed] [Google Scholar]
  7. Blatz A. L., Magleby K. L. Correcting single channel data for missed events. Biophys J. 1986 May;49(5):967–980. doi: 10.1016/S0006-3495(86)83725-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Cannell M. B., Nichols C. G. Effects of pipette geometry on the time course of solution change in patch clamp experiments. Biophys J. 1991 Nov;60(5):1156–1163. doi: 10.1016/S0006-3495(91)82151-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Clement J. P., 4th, Kunjilwar K., Gonzalez G., Schwanstecher M., Panten U., Aguilar-Bryan L., Bryan J. Association and stoichiometry of K(ATP) channel subunits. Neuron. 1997 May;18(5):827–838. doi: 10.1016/s0896-6273(00)80321-9. [DOI] [PubMed] [Google Scholar]
  10. Colquhoun D., Hawkes A. G. On the stochastic properties of single ion channels. Proc R Soc Lond B Biol Sci. 1981 Mar 6;211(1183):205–235. doi: 10.1098/rspb.1981.0003. [DOI] [PubMed] [Google Scholar]
  11. Colquhoun D., Hawkes A. G. Relaxation and fluctuations of membrane currents that flow through drug-operated channels. Proc R Soc Lond B Biol Sci. 1977 Nov 14;199(1135):231–262. doi: 10.1098/rspb.1977.0137. [DOI] [PubMed] [Google Scholar]
  12. 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]
  13. Drain P., Li L., Wang J. KATP channel inhibition by ATP requires distinct functional domains of the cytoplasmic C terminus of the pore-forming subunit. Proc Natl Acad Sci U S A. 1998 Nov 10;95(23):13953–13958. doi: 10.1073/pnas.95.23.13953. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Fan Z., Makielski J. C. Anionic phospholipids activate ATP-sensitive potassium channels. J Biol Chem. 1997 Feb 28;272(9):5388–5395. doi: 10.1074/jbc.272.9.5388. [DOI] [PubMed] [Google Scholar]
  15. Fan Z., Nakayama K., Hiraoka M. Multiple actions of pinacidil on adenosine triphosphate-sensitive potassium channels in guinea-pig ventricular myocytes. J Physiol. 1990 Nov;430:273–295. doi: 10.1113/jphysiol.1990.sp018291. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Findlay I., Faivre J. F. ATP-sensitive K channels in heart muscle. Spare channels. FEBS Lett. 1991 Feb 11;279(1):95–97. doi: 10.1016/0014-5793(91)80259-6. [DOI] [PubMed] [Google Scholar]
  17. Forestier C., Pierrard J., Vivaudou M. Mechanism of action of K channel openers on skeletal muscle KATP channels. Interactions with nucleotides and protons. J Gen Physiol. 1996 Apr;107(4):489–502. doi: 10.1085/jgp.107.4.489. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. 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]
  19. Gribble F. M., Tucker S. J., Ashcroft F. M. The essential role of the Walker A motifs of SUR1 in K-ATP channel activation by Mg-ADP and diazoxide. EMBO J. 1997 Mar 17;16(6):1145–1152. doi: 10.1093/emboj/16.6.1145. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Haynes L. W., Yau K. W. Single-channel measurement from the cyclic GMP-activated conductance of catfish retinal cones. J Physiol. 1990 Oct;429:451–481. doi: 10.1113/jphysiol.1990.sp018267. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Hilgemann D. W., Ball R. Regulation of cardiac Na+,Ca2+ exchange and KATP potassium channels by PIP2. Science. 1996 Aug 16;273(5277):956–959. doi: 10.1126/science.273.5277.956. [DOI] [PubMed] [Google Scholar]
  22. Huang C. L., Feng S., Hilgemann D. W. Direct activation of inward rectifier potassium channels by PIP2 and its stabilization by Gbetagamma. Nature. 1998 Feb 19;391(6669):803–806. doi: 10.1038/35882. [DOI] [PubMed] [Google Scholar]
  23. Inagaki N., Gonoi T., Clement J. P., 4th, Namba N., Inazawa J., Gonzalez G., Aguilar-Bryan L., Seino S., Bryan J. Reconstitution of IKATP: an inward rectifier subunit plus the sulfonylurea receptor. Science. 1995 Nov 17;270(5239):1166–1170. doi: 10.1126/science.270.5239.1166. [DOI] [PubMed] [Google Scholar]
  24. Inagaki N., Gonoi T., Clement J. P., Wang C. Z., Aguilar-Bryan L., Bryan J., Seino S. A family of sulfonylurea receptors determines the pharmacological properties of ATP-sensitive K+ channels. Neuron. 1996 May;16(5):1011–1017. doi: 10.1016/s0896-6273(00)80124-5. [DOI] [PubMed] [Google Scholar]
  25. Inagaki N., Gonoi T., Seino S. Subunit stoichiometry of the pancreatic beta-cell ATP-sensitive K+ channel. FEBS Lett. 1997 Jun 9;409(2):232–236. doi: 10.1016/s0014-5793(97)00488-2. [DOI] [PubMed] [Google Scholar]
  26. John S. A., Monck J. R., Weiss J. N., Ribalet B. The sulphonylurea receptor SUR1 regulates ATP-sensitive mouse Kir6.2 K+ channels linked to the green fluorescent protein in human embryonic kidney cells (HEK 293). J Physiol. 1998 Jul 15;510(Pt 2):333–345. doi: 10.1111/j.1469-7793.1998.333bk.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. 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]
  28. Koster J. C., Sha Q., Shyng S., Nichols C. G. ATP inhibition of KATP channels: control of nucleotide sensitivity by the N-terminal domain of the Kir6.2 subunit. J Physiol. 1999 Feb 15;515(Pt 1):19–30. doi: 10.1111/j.1469-7793.1999.019ad.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Lederer W. J., Nichols C. G. Nucleotide modulation of the activity of rat heart ATP-sensitive K+ channels in isolated membrane patches. J Physiol. 1989 Dec;419:193–211. doi: 10.1113/jphysiol.1989.sp017869. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Loussouarn G., Makhina E. N., Rose T., Nichols C. G. Structure and dynamics of the pore of inwardly rectifying K(ATP) channels. J Biol Chem. 2000 Jan 14;275(2):1137–1144. doi: 10.1074/jbc.275.2.1137. [DOI] [PubMed] [Google Scholar]
  31. MONOD J., WYMAN J., CHANGEUX J. P. ON THE NATURE OF ALLOSTERIC TRANSITIONS: A PLAUSIBLE MODEL. J Mol Biol. 1965 May;12:88–118. doi: 10.1016/s0022-2836(65)80285-6. [DOI] [PubMed] [Google Scholar]
  32. Matthews G., Watanabe S. Properties of ion channels closed by light and opened by guanosine 3',5'-cyclic monophosphate in toad retinal rods. J Physiol. 1987 Aug;389:691–715. doi: 10.1113/jphysiol.1987.sp016678. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Nichols C. G., Lederer W. J. Adenosine triphosphate-sensitive potassium channels in the cardiovascular system. Am J Physiol. 1991 Dec;261(6 Pt 2):H1675–H1686. doi: 10.1152/ajpheart.1991.261.6.H1675. [DOI] [PubMed] [Google Scholar]
  34. Nichols C. G., Lederer W. J., Cannell M. B. ATP dependence of KATP channel kinetics in isolated membrane patches from rat ventricle. Biophys J. 1991 Nov;60(5):1164–1177. doi: 10.1016/S0006-3495(91)82152-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Nichols C. G., Niggli E., Lederer W. J. Modulation of ATP-sensitive potassium channel activity by flash-photolysis of 'caged-ATP' in rat heart cells. Pflugers Arch. 1990 Jan;415(4):510–512. doi: 10.1007/BF00373635. [DOI] [PubMed] [Google Scholar]
  36. Nichols C. G., Shyng S. L., Nestorowicz A., Glaser B., Clement J. P., 4th, Gonzalez G., Aguilar-Bryan L., Permutt M. A., Bryan J. Adenosine diphosphate as an intracellular regulator of insulin secretion. Science. 1996 Jun 21;272(5269):1785–1787. doi: 10.1126/science.272.5269.1785. [DOI] [PubMed] [Google Scholar]
  37. Noma A. ATP-regulated K+ channels in cardiac muscle. Nature. 1983 Sep 8;305(5930):147–148. doi: 10.1038/305147a0. [DOI] [PubMed] [Google Scholar]
  38. Perozo E., Cortes D. M., Cuello L. G. Three-dimensional architecture and gating mechanism of a K+ channel studied by EPR spectroscopy. Nat Struct Biol. 1998 Jun;5(6):459–469. doi: 10.1038/nsb0698-459. [DOI] [PubMed] [Google Scholar]
  39. Picones A., Korenbrot J. I. Spontaneous, ligand-independent activity of the cGMP-gated ion channels in cone photoreceptors of fish. J Physiol. 1995 Jun 15;485(Pt 3):699–714. doi: 10.1113/jphysiol.1995.sp020763. [DOI] [PMC free article] [PubMed] [Google Scholar]
  40. Qin D. Y., Noma A. A new oil-gate concentration jump technique applied to inside-out patch-clamp recording. Am J Physiol. 1988 Oct;255(4 Pt 2):H980–H984. doi: 10.1152/ajpheart.1988.255.4.H980. [DOI] [PubMed] [Google Scholar]
  41. Qin D. Y., Takano M., Noma A. Kinetics of ATP-sensitive K+ channel revealed with oil-gate concentration jump method. Am J Physiol. 1989 Nov;257(5 Pt 2):H1624–H1633. doi: 10.1152/ajpheart.1989.257.5.H1624. [DOI] [PubMed] [Google Scholar]
  42. Shyng S. L., Nichols C. G. Membrane phospholipid control of nucleotide sensitivity of KATP channels. Science. 1998 Nov 6;282(5391):1138–1141. doi: 10.1126/science.282.5391.1138. [DOI] [PubMed] [Google Scholar]
  43. Shyng S., Ferrigni T., Nichols C. G. Control of rectification and gating of cloned KATP channels by the Kir6.2 subunit. J Gen Physiol. 1997 Aug;110(2):141–153. doi: 10.1085/jgp.110.2.141. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Shyng S., Ferrigni T., Nichols C. G. Regulation of KATP channel activity by diazoxide and MgADP. Distinct functions of the two nucleotide binding folds of the sulfonylurea receptor. J Gen Physiol. 1997 Dec;110(6):643–654. doi: 10.1085/jgp.110.6.643. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Shyng S., Nichols C. G. Octameric stoichiometry of the KATP channel complex. J Gen Physiol. 1997 Dec;110(6):655–664. doi: 10.1085/jgp.110.6.655. [DOI] [PMC free article] [PubMed] [Google Scholar]
  46. Sigworth F. J., Sine S. M. Data transformations for improved display and fitting of single-channel dwell time histograms. Biophys J. 1987 Dec;52(6):1047–1054. doi: 10.1016/S0006-3495(87)83298-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  47. Tanabe K., Tucker S. J., Matsuo M., Proks P., Ashcroft F. M., Seino S., Amachi T., Ueda K. Direct photoaffinity labeling of the Kir6.2 subunit of the ATP-sensitive K+ channel by 8-azido-ATP. J Biol Chem. 1999 Feb 12;274(7):3931–3933. doi: 10.1074/jbc.274.7.3931. [DOI] [PubMed] [Google Scholar]
  48. Taylor W. R., Baylor D. A. Conductance and kinetics of single cGMP-activated channels in salamander rod outer segments. J Physiol. 1995 Mar 15;483(Pt 3):567–582. doi: 10.1113/jphysiol.1995.sp020607. [DOI] [PMC free article] [PubMed] [Google Scholar]
  49. 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]
  50. Trapp S., Proks P., Tucker S. J., Ashcroft F. M. Molecular analysis of ATP-sensitive K channel gating and implications for channel inhibition by ATP. J Gen Physiol. 1998 Sep;112(3):333–349. doi: 10.1085/jgp.112.3.333. [DOI] [PMC free article] [PubMed] [Google Scholar]
  51. Tucker S. J., Gribble F. M., Proks P., Trapp S., Ryder T. J., Haug T., Reimann F., Ashcroft F. M. Molecular determinants of KATP channel inhibition by ATP. EMBO J. 1998 Jun 15;17(12):3290–3296. doi: 10.1093/emboj/17.12.3290. [DOI] [PMC free article] [PubMed] [Google Scholar]
  52. Tucker S. J., Gribble F. M., Zhao C., Trapp S., Ashcroft F. M. Truncation of Kir6.2 produces ATP-sensitive K+ channels in the absence of the sulphonylurea receptor. Nature. 1997 May 8;387(6629):179–183. doi: 10.1038/387179a0. [DOI] [PubMed] [Google Scholar]
  53. Zagotta W. N., Hoshi T., Aldrich R. W. Shaker potassium channel gating. III: Evaluation of kinetic models for activation. J Gen Physiol. 1994 Feb;103(2):321–362. doi: 10.1085/jgp.103.2.321. [DOI] [PMC free article] [PubMed] [Google Scholar]
  54. 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]

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

RESOURCES