J Biol Chem 1995 Aug 18;27033:19408-16.

Alcohols inhibit a cloned potassium channel at a discrete saturable site. Insights into the molecular basis of general anesthesia.

???displayArticle.abstract???
The molecular basis of general anesthetic action on membrane proteins that control ion transport is not yet understood. In a previous report (Covarrubias, M., and Rubin, E. (1993) Proc. Natl. Acad. Sci. 90, 6957-6960), we found that low concentrations of ethanol (17-170mM) selectively inhibited a noninactivating cloned K+ channel encoded by Drosophila Shaw2. Here, we have conducted equilibrium dos-inhibition experiments, single channel recording, and mutagenesis in vitro to study the mechanism underlying the inhibition of Shaw2K+ channels by a homologous series of n-alkanols (ethanol to 1-hexanol). The results showed that: (i) these alcohols inhibited Shaw2 whole-cell currents, the equilibrium dose-inhibition relations were hyperbolic, and competition experiments revealed the presence of a discrete site of action, possibly a hydrophobic pocket; (ii) this pocket may be part of the protein because n-alkanol sensitivity can be transferred to novel hybrid K+ channels composed of Shaw2 subunits and homologous ethanol-insensitive subunits: (iii) moreover, a hydrophobic point mutation within a cytoplasmic loop of an ethanol-insensitive K+ channel (human Kv3.4) was sufficient to allow significant inhibition by n-alkanols, with a dose-inhibition relation that closely resembled that of wildtype Shaw2 channels; and (iv) 1-butanol selectively inhibited long duration single channel openings in a manner consistent with a direct effect on channel gating. These results strongly suggest that a discrete site within the ion channel protein is the primary locus of alcohol and general anesthetic action.

???displayArticle.pubmedLink??? 7642622
???displayArticle.link??? J Biol Chem
???displayArticle.grants??? [+]

Species referenced: Xenopus
Genes referenced: kcnc2 kcnc4