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Regulation of deactivation by an amino terminal domain in human ether-à-go-go-related gene potassium channels.
J Gen Physiol. 1998 Nov; 112(5):637-47.JG

Abstract

Abnormalities in repolarization of the cardiac ventricular action potential can lead to life-threatening arrhythmias associated with long QT syndrome. The repolarization process depends upon the gating properties of potassium channels encoded by the human ether-à-go-go-related gene (HERG), especially those governing the rate of recovery from inactivation and the rate of deactivation. Previous studies have demonstrated that deletion of the NH2 terminus increases the deactivation rate, but the mechanism by which the NH2 terminus regulates deactivation in wild-type channels has not been elucidated. We tested the hypothesis that the HERG NH2 terminus slows deactivation by a mechanism similar to N-type inactivation in Shaker channels, where it binds to the internal mouth of the pore and prevents channel closure. We found that the regulation of deactivation by the HERG NH2 terminus bears similarity to Shaker N-type inactivation in three respects: (a) deletion of the NH2 terminus slows C-type inactivation; (b) the action of the NH2 terminus is sensitive to elevated concentrations of external K+, as if its binding along the permeation pathway is disrupted by K+ influx; and (c) N-ethylmaleimide, covalently linked to an aphenotypic cysteine introduced within the S4-S5 linker, mimics the N deletion phenotype, as if the binding of the NH2 terminus to its receptor site were hindered. In contrast to N-type inactivation in Shaker, however, there was no indication that the NH2 terminus blocks the HERG pore. In addition, we discovered that separate domains within the NH2 terminus mediate the slowing of deactivation and the promotion of C-type inactivation. These results suggest that the NH2 terminus stabilizes the open state and, by a separate mechanism, promotes C-type inactivation.

Authors+Show Affiliations

Department of Physiology, University of Wisconsin-Madison Medical School, Madison, Wisconsin 53706, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9806971

Citation

Wang, J, et al. "Regulation of Deactivation By an Amino Terminal Domain in Human Ether-à-go-go-related Gene Potassium Channels." The Journal of General Physiology, vol. 112, no. 5, 1998, pp. 637-47.
Wang J, Trudeau MC, Zappia AM, et al. Regulation of deactivation by an amino terminal domain in human ether-à-go-go-related gene potassium channels. J Gen Physiol. 1998;112(5):637-47.
Wang, J., Trudeau, M. C., Zappia, A. M., & Robertson, G. A. (1998). Regulation of deactivation by an amino terminal domain in human ether-à-go-go-related gene potassium channels. The Journal of General Physiology, 112(5), 637-47.
Wang J, et al. Regulation of Deactivation By an Amino Terminal Domain in Human Ether-à-go-go-related Gene Potassium Channels. J Gen Physiol. 1998;112(5):637-47. PubMed PMID: 9806971.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Regulation of deactivation by an amino terminal domain in human ether-à-go-go-related gene potassium channels. AU - Wang,J, AU - Trudeau,M C, AU - Zappia,A M, AU - Robertson,G A, PY - 1998/11/10/pubmed PY - 1998/11/10/medline PY - 1998/11/10/entrez SP - 637 EP - 47 JF - The Journal of general physiology JO - J Gen Physiol VL - 112 IS - 5 N2 - Abnormalities in repolarization of the cardiac ventricular action potential can lead to life-threatening arrhythmias associated with long QT syndrome. The repolarization process depends upon the gating properties of potassium channels encoded by the human ether-à-go-go-related gene (HERG), especially those governing the rate of recovery from inactivation and the rate of deactivation. Previous studies have demonstrated that deletion of the NH2 terminus increases the deactivation rate, but the mechanism by which the NH2 terminus regulates deactivation in wild-type channels has not been elucidated. We tested the hypothesis that the HERG NH2 terminus slows deactivation by a mechanism similar to N-type inactivation in Shaker channels, where it binds to the internal mouth of the pore and prevents channel closure. We found that the regulation of deactivation by the HERG NH2 terminus bears similarity to Shaker N-type inactivation in three respects: (a) deletion of the NH2 terminus slows C-type inactivation; (b) the action of the NH2 terminus is sensitive to elevated concentrations of external K+, as if its binding along the permeation pathway is disrupted by K+ influx; and (c) N-ethylmaleimide, covalently linked to an aphenotypic cysteine introduced within the S4-S5 linker, mimics the N deletion phenotype, as if the binding of the NH2 terminus to its receptor site were hindered. In contrast to N-type inactivation in Shaker, however, there was no indication that the NH2 terminus blocks the HERG pore. In addition, we discovered that separate domains within the NH2 terminus mediate the slowing of deactivation and the promotion of C-type inactivation. These results suggest that the NH2 terminus stabilizes the open state and, by a separate mechanism, promotes C-type inactivation. SN - 0022-1295 UR - https://www.unboundmedicine.com/medline/citation/9806971/Regulation_of_deactivation_by_an_amino_terminal_domain_in_human_ether_à_go_go_related_gene_potassium_channels_ L2 - https://rupress.org/jgp/article-lookup/doi/10.1085/jgp.112.5.637 DB - PRIME DP - Unbound Medicine ER -