The rat beta 1-subunit of the GABAA receptor forms a picrotoxin-sensitive anion channel open in the absence of GABA.
The structural basis of GABA-gated chloride channels in mammalian brain is presently explored by the functional expression of cDNAs coding for the alpha, beta or gamma-subunits of the receptor and their isoforms. In this context, we expressed the cloned cDNA coding for the rat beta 1-subunit of the GABAA receptor in the Xenopus oocyte. Surprisingly, efficient expression of a functional ion channel was found. The channel was anion-selective, and able to open in the absence of GABA. Since this channel could be shunt by the GABA-channel blocker picrotoxin, we conclude that the beta 1-subunit of the GABAA receptor is sufficient to form binding sites for picrotoxin.
Sigel
E
E
Institute of Pharmacology, University of Bern, Switzerland.
Baur
R
R
Malherbe
P
P
Möhler
H
H
D000818:Animals; D000838:Anions; D002243:Carbolines / Q000494:pharmacology; D003975:Diazepam / Q000494:pharmacology; D007473:Ion Channels; D046911:Macromolecular Substances; D008564:Membrane Potentials; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D011963:Receptors, GABA-A / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D014982:Xenopus laevis; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D000838:Anions; D002243:Carbolines; D003975:Diazepam; D007473:Ion Channels; D046911:Macromolecular Substances; D010852:Picrotoxin; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; C034818:methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate