Evidence that the M2 membrane-spanning region lines the ion channel pore of the nicotinic receptor
Abstract
Site-directed mutagenesis and expression in Xenopus oocytes were used to study acetylcholine receptors in which serine residues (i) were replaced by alanines (alpha, delta subunits) or (ii) replaced a phenylalanine (beta subunit) at a postulated polar site within the M2 transmembrane helix. As the number of serines decreased, there were decreases in the residence time and consequently the equilibrium binding affinity of QX-222, a quaternary ammonium anesthetic derivative thought to bind within the open channel. Receptors with three serine-to-alanine mutations also displayed a selective decrease in outward single-channel currents. Both the direction of this rectification and the voltage dependence of QX-222 blockade suggest that the residues mutated are within the aqueous pore of the receptor and near its cytoplasmic (inner) surface.
Additional Information
© 1988 American Association for the Advancement of Science. 30 June 1988; Accepted 11 October 1988. We thank M. Fearey and A. Charnet for help with the oocytes, L. Czyzyk for expert technical help with the mutagenesis, and G. Eisenman for discussion. This research was supported by grants from NIH (NS-11756) and the Muscular Dystrophy Association of America and by postdoctoral fellowships to R.J.L. (NS-8083) and to P.C. (Bourse Lavoisier and FRM, France).Additional details
- Eprint ID
- 54199
- DOI
- 10.1126/science.2462281
- Resolver ID
- CaltechAUTHORS:20150128-145454703
- NS-11756
- NIH
- Muscular Dystrophy Association
- NS-8083
- NIH
- Bourse Lavoisier
- Fondation pour la Recherche Médicale
- Created
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2015-01-28Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field