Pharmacology of recombinant gamma-aminobutyric acidA receptors rendered diazepam-insensitive by point-mutated alpha-subunits.
Amino acids in the alpha- and gamma-subunits contribute to the benzodiazepine binding site of GABA(A)-receptors. We show that the mutation of a conserved histidine residue in the N-terminal extracellular segment (alpha1H101R, alpha2H101R, alpha3H126R, and alpha5H105R) results not only in diazepam-insensitivity of the respective alphaxbeta2,3gamma2-receptors but also in an increased potentiation of the GABA-induced currents by the partial agonist bretazenil. Furthermore, Ro 15-4513, an inverse agonist at wild-type receptors, acts as an agonist at all mutant receptors. This conserved molecular switch can be exploited to identify the pharmacological significance of specific GABA(A)-receptor subtypes in vivo.
Benson
J A
JA
Institute of Pharmacology, University of Zürich, Switzerland.
Löw
K
K
Keist
R
R
Mohler
H
H
Rudolph
U
U
D000595:Amino Acid Sequence; D000818:Animals; D001386:Azides / Q000494:pharmacology; D001483:Base Sequence; D001569:Benzodiazepines / Q000494:pharmacology; D001570:Benzodiazepinones / Q000494:pharmacology; D002460:Cell Line; D003975:Diazepam / Q000494:pharmacology*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D018408:Patch-Clamp Techniques; D051381:Rats; D011963:Receptors, GABA-A / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000187:drug effects / Q000235:genetics
D001386:Azides; D001570:Benzodiazepinones; D009838:Oligodeoxyribonucleotides; D011963:Receptors, GABA-A; D011994:Recombinant Proteins; D001569:Benzodiazepines; C042957:Ro 15-4513; C054626:bretazenil; D003975:Diazepam