ISSN:
1369-1600
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Medizin
Notizen:
Amino acids (AAs) in the extracellular portion of the transmembrane domain of several inhibitory ligand-gated ion channels participate in an alcohol binding site. To extend these studies to neuronal nicotinic acetylcholine receptors (nAChRs), we focused on an AA (L262) located in the same region of the second transmembrane domain of the α2 subunit of neuronal nAChRs. Single-point mutation of α2L262 was carried out, the resulting α2 subunits co-expressed with wild-type β4 subunits in Xenopus laevis oocytes, and studied using two-electrode voltage clamp. Ethanol enhancement of ACh responses was diminished [α2(L262F)β4] or abolished [α2(L262G)β4, α2(L262S)β4 and α2(L262A)β4]. Mutation of the homologous AA in β4 [β4(L258A)] did not modify the ethanol modulation and the mutation in α2 was dominant, because ethanol did not enhance ACh responses in α2(L262A)β4(L258A) nAChRs. n-Alcohols (ethanol through octanol) were applied to α2(L262A)β4 nAChRs. As described previously for other nAChRs, short-chain alcohols enhanced, intermediate-chain alcohols had no effect and long-chain alcohols inhibited ACh responses in the wild-type receptor. For α2(L262A)β4 nAChRs the alcohol enhancing effect was absent, and the alcohol inhibitory action was increased. Although this suggests removal of an alcohol enhancing site through mutagenesis, we cannot rule out the enhancement of action at an alcohol inhibitory site.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1080/13556210310001602220
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