Point mutations affecting antagonist affinity and agonist dependent gating of GABAA receptor channels.

Détails

ID Serval
serval:BIB_F209B7485E32
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Point mutations affecting antagonist affinity and agonist dependent gating of GABAA receptor channels.
Périodique
EMBO Journal
Auteur(s)
Sigel E., Baur R., Kellenberger S., Malherbe P.
ISSN
0261-4189[print], 0261-4189[linking]
Statut éditorial
Publié
Date de publication
1992
Volume
11
Numéro
6
Pages
2017-2023
Langue
anglais
Résumé
Two variant amino acid sequences, which differ in a single amino acid residue, have been reported for the alpha 1-subunit of the rat brain GABAA receptor. We separately co-expressed these two variants in Xenopus oocytes, in combination with beta 2 and gamma 2. This experiment showed that substitution of alpha 1-Phe64 by Leu strongly decreases the apparent affinity for GABA dependent channel gating from 6 microM to 1260 microM. Starting from this observation, we used in vitro mutagenesis to obtain information relevant for the localization of the agonist/antagonist binding site in the GABAA receptor. Homologous mutation in alpha 5 had similar consequences for alpha 5 beta 2 gamma 2. Homologous mutation in beta 2 and gamma 2 resulted in intermediate and small shifts in EC50, respectively. The apparent affinities of the competitive antagonists bicuculline methiodide and SR95531, the latter sharing close structural similarity with the agonist GABA, were decreased 60- to 200-fold by these mutations in alpha-subunits. Interestingly, these affinities remained nearly unaffected upon introduction of the homologous mutations in beta 2 and gamma 2, or upon mutation of the neighbouring amino acid in alpha 1, Phe65 to Leu. These results suggest close functional and structural association of alpha-subunits with the agonist/antagonist binding site, and involvement of N-terminal portions of the extracellular domains of all subunits in the gating of the channel.
Mots-clé
Amino Acid Sequence, Animals, Base Sequence, Bicuculline/analogs & derivatives, Bicuculline/pharmacology, Brain/physiology, Ion Channel Gating, Ion Channels/drug effects, Ion Channels/genetics, Kinetics, Macromolecular Substances, Molecular Sequence Data, Mutagenesis, Site-Directed, Oligodeoxyribonucleotides, Oocytes/physiology, Rats, Receptors, GABA-A/drug effects, Receptors, GABA-A/genetics, Xenopus, gamma-Aminobutyric Acid/pharmacology
Pubmed
Web of science
Création de la notice
24/01/2008 13:45
Dernière modification de la notice
03/03/2018 22:39
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