Consequences of the Evolution of the GABAA Receptor Gene Family

1. This paper reviews the evolution of the family of genes present in mammals and other vertebrates that encode $γ$-aminobutyric acid (GABA) type A (GABAA) receptors, which are the major inhibitory neurotransmitter receptors in the central nervous system (CNS). In mammals, 16 different polypeptides ($α$1--$α$6, $β$1--$β$3, $γ$1--$γ$3, $δ$, $ε$, $π$, and $θ$) have been identified, using recombinant DNA techniques, each of which is encoded by a distinct gene. The products of these genes assemble in diverse combinations to form a variety of receptor subtypes that have different sensitivities to a number of clinically relevant compounds, such as the benzodiazepines (BZs)