title: Molecular analysis of the site for 2-arachidonylglycerol (2-AG) on the β₂ subunit of GABA(A) receptors.
abstract: 2-arachidonyl glycerol (2-AG) allosterically potentiates GABA(A) receptors via a binding site located in transmembrane segment M4 of the β₂ subunit. Two amino acid residues have been described that are essential for this effect. With the aim to further describe this potential drug target, we performed a cysteine scanning of the entire M4 and part of M3. All four residues in M4 affecting the potentiation here and the two already identified residues locate to the same side of the α-helix. This side is exposed to M3, where further residues were identified. From the fact that the important residues span > 18 Å, we conclude that the hydrophobic tail of the bound 2-AG molecule must be near linear and that the site mainly locates to the inner leaflet but stretches far into the membrane. The influence of the structure of the head group of the ligand molecule on the activity of the molecule was also investigated. We present a model of 2-AG docked to the GABA(A) receptor.
authors.affiliation: Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.
authors.forename: Roland
authors.initials: R
authors.lastname: Baur
authors.forename: Marie
authors.initials: M
authors.lastname: Kielar
authors.forename: Lars
authors.initials: L
authors.lastname: Richter
authors.forename: Margot
authors.initials: M
authors.lastname: Ernst
authors.forename: Gerhard F
authors.initials: GF
authors.lastname: Ecker
authors.forename: Erwin
authors.initials: E
authors.lastname: Sigel
mesh_terms: D000818:Animals; D001095:Arachidonic Acids / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001665:Binding Sites; D003545:Cysteine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D063388:Endocannabinoids / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004983:Ethanolamines / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D005260:Female; D005989:Glycerides / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics / Q000502:physiology; D009865:Oocytes / Q000378:metabolism; D017354:Point Mutation / Q000235:genetics / Q000502:physiology; D053284:Polyunsaturated Alkamides / Q000494:pharmacology; D043884:Receptor, Cannabinoid, CB1 / Q000819:agonists; D011963:Receptors, GABA-A / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D001095:Arachidonic Acids; D063388:Endocannabinoids; D004983:Ethanolamines; D005231:Fatty Acids, Unsaturated; C495710:GABRB2 protein, human; D005989:Glycerides; D053284:Polyunsaturated Alkamides; D043884:Receptor, Cannabinoid, CB1; D011963:Receptors, GABA-A; C083632:7,10,13,16-docosatetraenylethanolamide; C094503:glyceryl 2-arachidonate; D003545:Cysteine