gamma-Aminobutyric acid type A receptor point mutation increases the affinity of compounds for the benzodiazepine site.
Recombinantly expressed gamma-aminobutyric acid type A (GABAA) receptors consisting of alpha 1, beta 2, and gamma 2 subunits contain a binding site for benzodiazepines that differs in its properties from that of alpha 3 beta 2 gamma 2 receptors. Amino acid substitutions between the GABAA receptor alpha subunits were analyzed for their effect on the binding of compounds to the benzodiazepine site. By converting ever smaller regions of the alpha 3 subunit sequence to that of the alpha 1 subunit, we show that a single substitution (glycine for glutamic acid) increases the affinity for several compounds approximately 10-fold without changing the affinity for nonselective compounds. Hence, the identified amino acids may interact directly with the ligand and define part of the benzodiazepine binding sites in these receptors.
Pritchett
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DB
Department of Pediatrics, University of Pennsylvania, Philadelphia 19104.
Seeburg
P H
PH
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D002460:Cell Line; D002678:Chimera; D005442:Flumazenil / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015345:Oligonucleotide Probes; D051381:Rats; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D046911:Macromolecular Substances; D015345:Oligonucleotide Probes; D011963:Receptors, GABA-A; D005442:Flumazenil