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Archives of Pharmacal Research

, Volume 29, Issue 4, pp 310–317 | Cite as

Chemical modification of the human ether-a-go-go-related gene (HERG) K+ current by the amino-group reagent trinitrobenzene sulfonic acid

  • Su-Hyun Jo
  • Se-Young Choi
  • Ji-Hyun Yun
  • Young-Sang Koh
  • Won-Kyung Ho
  • Chin O. Lee
Articles Drug Development

Abstract

We investigated the effects of trinitrobenzene sulfonic acid (TNBS), an amino-group reagent, on the humanether-a-go-go-related gene (HERG) K+ channels expressed inXenopus oocytes. TNBS neutralizes the positively charged amino-agroups of peptideN-terminal and lysine residues. External application of TNBS at 10 mM for 5 min irreversibly shifted the curves for currents at the end of the pulse and tail currents of HERG to a more negative potential and decreased the maximal amplitude of the Itail curve (Itail, max). TNBS had little effect on either the activated current-voltage relationship or the reversal potential of HERG current, indicating that TNBS did not change ion selectivity properties. TNBS shifted the time constant curves of both activation and deactivation of the HERG current to a more hyperpolarized potential; TNBS's effect was greater on channel opening than channel closing. External H+ is known to inhibit HERG current by shifting V1/2 to the right and decreasing Itail, max. TNBS enhanced the blockade of external H+ by exaggerating the effect of H+ on Itail, max, not on V1/2. Our data provide evidence for the presence of essential amino-groups that are associated with the normal functioning of the HERG channel and evidence that these groups modify the blocking effect of external H+ on the current.

Key words

H+ HERG channel LQT Rapidly activating delayed rectifier K+ current Torsades de pointes Trinitrobenzene sulfonic acid 

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References

  1. Bell, J. E. and Bell, E. T., Proteins and enzyme. pp. 499. Prentice-Hall, Englewood cliffs, NJ, (1988).Google Scholar
  2. Cahalan, M. D. and Pappone, P. A., Chemical modification of potassium channel gating in frog myelinated nerve by trinitrobenzene sulphonic acid.J. Physiol., 342, 119–143 (1983).PubMedGoogle Scholar
  3. Curran, M. E., Splawski, I., Timothy, K. W., Vincent, G. M., Green, E. D., and Keating, M. T., A molecular basis for cardiac arrhythmia: HERG mutations cause long QT syndrome.Cell, 80, 795–803 (1995).PubMedCrossRefGoogle Scholar
  4. Dun, W., Jiang, M., and Tseng, G. N., Allosteric effects of mutations in the extracellular S5-P loop on the gating and ion permeation properties of the HERG potassium channel.Pflugers Arch., 439, 141–149 (1999).PubMedCrossRefGoogle Scholar
  5. Freedman, R. B. and Radda, G. K., The reaction of 2,4,6-trinitrobenzenesulphonic acid with amino acids, peptides and proteins.Biochem. J., 108, 383–391 (1968).PubMedGoogle Scholar
  6. Green, W. N. and Andersen, O. S., Surface charges and ion channel function.Annu. Rev. Physiol., 53, 341–359 (1991).PubMedCrossRefGoogle Scholar
  7. Hille, B., Potassium channels in myelinated nerve. Selective permeability to small cations.J. Gen. Physiol., 61, 669–686 (1973).PubMedCrossRefGoogle Scholar
  8. Hille, B., Ionic channels of excitable membranes. 2nd edn. Sinauer Associates Inc, Sunderland, Mass, pp. 469–461, (1992).Google Scholar
  9. Jo, S. H., Youm, J. B., Kim, I., Lee, C. O., Earm, Y. E., and Ho, W. K., Blockade of HERG channels expressed in Xenopus oocytes by external H+.Pflugers Arch., 438, 23–29 (1999).PubMedCrossRefGoogle Scholar
  10. Jo, S. H., Youm, J. B., Lee C. O., Earm, Y. E., and Ho, W. K., Blockade of the HERG human cardiac K(+) channel by the antidepressant drug amitriptyline.Br. J. Pharmacol., 129, 1474–1480 (2000).PubMedCrossRefGoogle Scholar
  11. Kupershmidt, S., Snyders, D. J., Raes, A., and Roden, D. M. A K+ channel splice variant common in human heart lacks a C-terminal domain required for expression of rapidly activating delayed rectifier current.J. Biol. Chem., 273, 27231–27235 (1998).PubMedCrossRefGoogle Scholar
  12. Lee, S. Y., Choi, S. Y., Youm, J. B., Ho, W. K., Earm, Y. E., Lee, C. O., and Jo, S. H., Block of HERG human K(+) channel and IKr of guinea pig cardiomyocytes by chlorpromazine.J. Cardiovasc. Pharmacol., 43, 706–714 (2004).PubMedCrossRefGoogle Scholar
  13. Means, G. E. and Feeny, R. E., Chemical Modification of Proteins, pp. 254. Holden-Day Inc., San Francisco (1971).Google Scholar
  14. Sanguinetti, M. C., Jiang, C., Curran, M. E., and Keating, M. T., A mechanistic link between an inherited and an acquired cardiac arrhythmia: HERG encodes the IKr potassium channel.Cell, 81, 299–307 (1995).PubMedCrossRefGoogle Scholar
  15. Sanguinetti, M. C. and Xu, Q. P., Mutations of the S4–S5 linker alter activation properties of HERG potassium channels expressed in Xenopus oocytes.J. Physiol., 514, 667–675 (1999).PubMedCrossRefGoogle Scholar
  16. Schauf, C. L. and Davis, F. A., Sensitivity of the sodium and potassium channels of Myxicola giant axons to changes in external pH.J. Gen. Physiol., 67, 185–195 (1976).PubMedCrossRefGoogle Scholar
  17. Snyders, D. J. and Chaudhary, A., High affinity open channel block by dofetilide of HERG expressed in a human cell line.Mol. Pharmacol., 49, 949–955 (1996).PubMedGoogle Scholar
  18. Spires, S. and Begenisich, T., Modification of potassium channel kinetics by histidine-specific reagents.J. Gen. Physiol., 96, 757–775 (1990).PubMedCrossRefGoogle Scholar
  19. Spires, S. and Begenisich, T., Modification of potassium channel kinetics by amino group reagents.J. Gen. Physiol., 99, 109–129 (1992a).PubMedCrossRefGoogle Scholar
  20. Spires, S. and Begenisich, T., Chemical properties of the divalent cation binding site on potassium channels.J. Gen. Physiol., 100, 181–193 (1992b).PubMedCrossRefGoogle Scholar
  21. Suessbrich, H., Waldegger, S., Lang, F., and Busch, A. E., Blockade of HERG channels expressed in Xenopus oocytes by the histamine receptor antagonists terfenadine and astemizole.FEBS Lett., 385, 77–80 (1996).PubMedCrossRefGoogle Scholar
  22. Trudeau, M. C., Warmke, J. W., Ganetzky, B., and Robertson, G. A., HERG, a human inward rectifier in the voltage-gated potassium channel family.Science, 269, 92–95 (1995).PubMedCrossRefGoogle Scholar
  23. Warmke, J. W. and Ganetzky, B., A family of potassium channel genes related to eag in Drosophila and mammals.Proc. Natl. Acad. Sci. U.S.A., 91, 3438–3442 (1991).CrossRefGoogle Scholar
  24. Zhou, Z., Gong, Q., Epstein, M. L., and January, C. T., HERG channel dysfunction in human long QT syndrome. Intracellular transport and functional defects.J. Biol. Chem., 273, 21061–21066 (1998).PubMedCrossRefGoogle Scholar

Copyright information

© The Pharmaceutical Society of Korea 2006

Authors and Affiliations

  • Su-Hyun Jo
    • 1
    • 2
  • Se-Young Choi
    • 3
  • Ji-Hyun Yun
    • 4
  • Young-Sang Koh
    • 4
  • Won-Kyung Ho
    • 5
  • Chin O. Lee
    • 2
  1. 1.Department of Physiology, College of MedicineCheju National UniversityJejuKorea
  2. 2.Department of Life SciencePohang University of Science and TechnologyPohangKorea
  3. 3.Department of Physiology and Dental Research Institute, College of DentistrySeoul National UniversitySeoulKorea
  4. 4.Department of Microbiology, College of MedicineCheju National UniversityJejuKorea
  5. 5.Department of Physiology, College of MedicineSeoul National UniversitySeoulKorea

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