The GABA-A receptor gene family: new targets for therapeutic intervention.

Until 1987, when the first GABA-A receptor subunit cDNAs were cloned and sequenced, it was thought that there were perhaps two subtypes of receptor in the brain. These were defined by the fact that benzodiazepines, which act through the GABA-A receptor, had two binding sites with different affinities. By 1991 it was known that the GABA-A receptor family existed as a family of subunits which coassembled to form a family of receptor subtypes in the brain. More recently, two additional GABA-A receptor subunits have been identified, epsilon and theta. The identification of these new members of the gene family, and the characterisation of the receptor subtypes into which they are incorporated, is reviewed.