The rat β1 -subunit of the GABAA receptor forms a picrotoxin-sensitive anion channel open in the absence of GABA

Abstract
The structural basis of GABA-gated chloride channels in mammalian brain is presently explored by the functonal expression of cDNAs coding for the α, β or γ-subunits of the receptor and their isoforms. In this context, we expressed the cloned cDNA coding for the rat β1-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 shut by the GABA-channel blocker picrotoxin, we conclude that the β1 -subunit of the GABAA receptor is sufficient to form binding sites for picrotoxin.