Forced subunit assembly in α1β2γ2 GABAA receptors: insight into the absolute arrangement

By S. Baumann, R. Baur, E. Sigel. 2002

245 citations recorded by the source corpus.

Abstract The major isoform of the γ-aminobutyric acid type A (GABAA) receptor is thought to be composed of 2α1, 2β2, and 1γ2 subunit(s), which surround the ion pore. Definite evidence for the subunit arrangement is lacking. We show here that GABAA receptor subunits can be concatenated to a trimer that can be functionally expressed upon combination with a dimer. Many combinations did not result in the functional expression. In contrast, four different combinations of triple subunits with dual subunit constructs, all resulting in the identical pentameric receptor γ2β2α1β2α1, could be successfully expressed in Xenopus oocytes. We characterized the functional properties of these receptors in respect to agonist, competitive antagonist, and diazepam sensitivity. All properties were similar to those of wild type α1β2γ2 GABAAreceptors. Thus, together with information on the crystal structure of the homologous acetylcholine-binding protein (Brejc, K., van Dijk, W. J., Klaassen, R. V., Schuurmans, M., van Der Oost, J., Smit, A. B., and Sixma, T. K., (2001) Nature411, 269–276, we provide evidence for an arrangement γ2β2α1β2α1, counterclockwise when viewed from the synaptic cleft. Forced subunit assembly will also allow receptors containing different subunit isoforms or mutant subunits to be expressed, each in a desired position. The methods established here should be applicable to the entire ion channel family comprising nicotinic acetylcholine, glycine, and 5HT3 receptors.

Subfields: Cellular and Molecular Neuroscience, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/e68658f393093850ceb63ef0ce9d4d724d85b812

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In Cellular and Molecular Neuroscience

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Citations in the corpus

International Union of Pharmacology. LXX. Subtypes of γ-Aminobutyric AcidA Receptors: Classification on the Basis of Subunit Composition, Pharmacology, and Function. Update (2008, background): “Concat-enated subunits may be of use in determining specific subunit composition and wheel arrangement (Im et al., 1995; Baumann et al., 2002; Minier and Sigel, 2004; Boileau et al., 2005; Sigel et al., 2006), although this approach also has a number of problems (Ericksen and Boileau, 2007).”
GABAA Receptors: Subtypes Provide Diversity of Function and Pharmacology (2008, unknown): “This conclusion was confirmed in several recombinant receptor studies, some of which also were able to determine the subunit arrangement of receptors composed of 2a, 2b and 1g subunits (Tretter et al., 1997; Baumann et al., 2002).”