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Human Ether-à-go-go–related Gene K+ Channel Gating Probed with Extracellular Ca2+
| Content Provider | Scilit |
|---|---|
| Author | Johnson, J. P. Mullins, Franklin M. Bennett, Paul B. |
| Copyright Year | 1999 |
| Description | Journal: The Journal of general physiology Human ether-à-go-go–related gene (HERG) encoded $K^{+}$ channels were expressed in Chinese hamster ovary (CHO-K1) cells and studied by whole-cell voltage clamp in the presence of varied extracellular $Ca^{2+}$ concentrations and physiological external $K^{+}$. Elevation of external $Ca^{2+}$ from 1.8 to 10 mM resulted in a reduction of whole-cell $K^{+}$ current amplitude, slowed activation kinetics, and an increased rate of deactivation. The midpoint of the voltage dependence of activation was also shifted +22.3 ± 2.5 mV to more depolarized potentials. In contrast, the kinetics and voltage dependence of channel inactivation were hardly affected by increased extracellular $Ca^{2+}$. Neither $Ca^{2+}$ screening of diffuse membrane surface charges nor open channel block could explain these changes. However, selective changes in the voltage-dependent activation, but not inactivation gating, account for the effects of $Ca^{2+}$ on Human ether-à-go-go–related gene current amplitude and kinetics. The differential effects of extracellular $Ca^{2+}$ on the activation and inactivation gating indicate that these processes have distinct voltage-sensing mechanisms. Thus, $Ca^{2+}$ appears to directly interact with externally accessible channel residues to alter the membrane potential detected by the activation voltage sensor, yet $Ca^{2+}$ binding to this site is ineffective in modifying the inactivation gating machinery. |
| Related Links | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2217168/pdf http://jgp.rupress.org/content/113/4/565.full.pdf |
| ISSN | 00221295 |
| DOI | 10.1085/jgp.113.4.565 |
| Journal | The Journal of general physiology |
| Issue Number | 4 |
| Volume Number | 113 |
| Language | English |
| Publisher | Rockefeller University Press |
| Publisher Date | 1999-04-01 |
| Access Restriction | Open |
| Subject Keyword | Journal: The Journal of general physiology Human Ether-à-go-go–related Gene Potassium Ion Channel Gating Kinetics Membrane Surface Charge Divalent Cation |
| Content Type | Text |
| Resource Type | Article |
| Subject | Physiology |
