title: Relative positioning of classical benzodiazepines to the γ2-subunit of GABAA receptors.
abstract: GABAA receptors are the major inhibitory neurotransmitter receptors in the brain. Benzodiazepine exert their action via a high affinity-binding site at the α/γ subunit interface on some of these receptors. Diazepam has sedative, hypnotic, anxiolytic, muscle relaxant, and anticonvulsant effects. It acts by potentiating the current evoked by the agonist GABA. Understanding specific interaction of benzodiazepines in the binding pocket of different GABAA receptor isoforms might help to separate these divergent effects. As a first step, we characterized the interaction between diazepam and the major GABAA receptor isoform α1β2γ2. We mutated several amino acid residues on the γ2-subunit assumed to be located near or in the benzodiazepine binding pocket individually to cysteine and studied the interaction with three ligands that are modified with a cysteine-reactive isothiocyanate group (-NCS). When the reactive NCS group is in apposition to the cysteine residue this leads to a covalent reaction. In this way, three amino acid residues, γ2Tyr58, γ2Asn60, and γ2Val190 were located relative to classical benzodiazepines in their binding pocket on GABAA receptors.
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern , CH-3012 Bern, Switzerland.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Middendorp
authors.forename: Evelyn
authors.initials: E
authors.lastname: Hurni
authors.forename: Matthias
authors.initials: M
authors.lastname: Schönberger
authors.forename: Marco
authors.initials: M
authors.lastname: Stein
authors.forename: Michael
authors.initials: M
authors.lastname: Pangerl
authors.forename: Dirk
authors.initials: D
authors.lastname: Trauner
authors.forename: Erwin
authors.initials: E
authors.lastname: Sigel
mesh_terms: D000818:Animals; D001569:Benzodiazepines / Q000378:metabolism*; D066241:Carbon-13 Magnetic Resonance Spectroscopy; D066244:Proton Magnetic Resonance Spectroscopy; D011869:Radioligand Assay; D011963:Receptors, GABA-A / Q000737:chemistry / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D014981:Xenopus
chemical_list: D011963:Receptors, GABA-A; D001569:Benzodiazepines