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Two neighboring residues of loop A of the α1 subunit point towards the benzodiazepine binding site of GABAA receptors

Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, CH-3012 Bern, Switzerland.
FEBS Letters (Impact Factor: 3.34). 11/2007; 581(24):4718-22. DOI: 10.1016/j.febslet.2007.08.068
Source: PubMed

ABSTRACT Benzodiazepines are widely used drugs exerting sedative, anxiolytic, muscle relaxant, and anticonvulsant effects by acting through specific high affinity binding sites on some GABA(A) receptors. It is important to understand how these ligands are positioned in this binding site. We are especially interested here in the conformation of loop A of the alpha(1)beta(2)gamma(2) GABA(A) receptor containing a key residue for the interaction of benzodiazepines: alpha(1)H101. We describe a direct interaction of alpha(1)N102 with a diazepam- and an imidazobenzodiazepine-derivative. Our observations help to better understand the conformation of this region of the benzodiazepine pocket in GABA(A) receptor.

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    • " model - ing . It should however be noted that sequence identity of these two proteins only amounts to about 18% and that the binding pocket is to a large extent made up by loop structures Fig . 7 Positioning of diazepam in the benzodiazepine - binding pocket of a 1 b 2 c 2 receptors . The – Cl atom ( dark green ) points to a 1 H101 and a 1 N102 ( Tan et al . 2007a ) and to a 1 G157 , a 1 V202 and a 1 V211 ( Tan et al . 2007b ) , whereas the opposite hydrogen ( yellow ) attached to the - C - 3 atom points to a 1 S205 and a 1 T206 . An immobilized diazepam affinity column has been used to isolate the GABA A receptors form solubilized bovine brain ( Sigel et al . 1982 , 1983 ) . Diazepam was at - ta"
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    Journal of Neurochemistry 10/2009; 111(5):1264-73. DOI:10.1111/j.1471-4159.2009.06419.x · 4.24 Impact Factor
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    • "A caveat is that affinity-labeling could " capture " a minor orientation that does not contribute appreciably to the action of reversibly bound BZDs. DZ-NCS also modifies ␣ 1 N102C and ␥ 2 A79C, albeit with lower efficiency (Tan et al., 2007a), and an NCS analog of Ro 15-4513, which lacks the pendant phenyl and may have greater freedom to orient in the binding pocket, reacts with ␣ 1 residues 101, 157, 202, and 211. Confidence that DZ-NCS covalently linked to ␣1 residue 101 occupies the binding pocket similarly to reversibly bound DZ is increased because ␣ 1 His101 is a known contact residue that is critical for pharmacological activity of BZDs (McKernan et al., 1995; Davies et al., 1996; Duncalfe et al., 1996; Smith and Olsen, 2000) and because covalent linkage of DZ-NCS results in irreversible potentiation comparable with that produced by DZ (Berezhnoy et al., 2004). "
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    • "In the NCS compound, the -Cl group is replaced by –NCS (Fig. 1). The synthesis is described elsewhere (Berezhnoy et al. 2004; Tan et al. 2007b). The compound was dissolved in DMSO (Dimethyl sulfoxide) at a concentration of 10 mM and kept at )20°C. "
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