In vivo functional role of the Drosophila hyperkinetic beta subunit in gating and inactivation of Shaker K+ channels

Biophysical Journal
J W Wang, C F Wu

Abstract

The physiological roles of the beta, or auxiliary, subunits of voltage-gated ion channels, including Na+, Ca2+, and K+ channels, have not been demonstrated directly in vivo. Drosophila Hyperkinetic (Hk) mutations alter a gene encoding a homolog of the mammalian K+ channel beta subunit, providing a unique opportunity to delineate the in vivo function of auxiliary subunits in K+ channels. We found that the Hk beta subunit modulates a wide range of the Shaker (Sh) K+ current properties, including its amplitude, activation and inactivation, temperature dependence, and drug sensitivity. Characterizations of the existing mutants in identified muscle cells enabled an analysis of potential mechanisms of subunit interactions and their functional consequences. The results are consistent with the idea that via hydrophobic interaction, Hk beta subunits modulate Sh channel conformation in the cytoplasmic pore region. The modulatory effects of the Hk beta subunit appeared to be specific to the Sh alpha subunit because other voltage- and Ca(2+)-activated K+ currents were not affected by Hk mutations. The mutant effects were especially pronounced near the voltage threshold of IA activation, which can disrupt the maintenance of the quiescent st...Continue Reading

Citations

Feb 24, 2007·Behavior Genetics·Nadia ScantleburyAna Regina Campos
Feb 28, 2004·Trends in Cardiovascular Medicine·J Xu, M Li
Oct 16, 2009·Journal of Neurophysiology·Stefanie Ryglewski, Carsten Duch
Aug 8, 2008·Journal of Neurophysiology·Ricardo H PinedaAngeles B Ribera
Jun 18, 2002·The Journal of Physiology·Meredith A LazaroffAngeles B Ribera
Oct 11, 2019·Journal of Biological Rhythms·Lauren E Foley, Patrick Emery
Apr 16, 1998·The Journal of Biological Chemistry·G F WilsonB Ganetzky
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May 26, 2009·Molecular and Cellular Neurosciences·Fengqiu DiaoSusan Tsunoda

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