GABA (γ-aminobutyric acid) is the essential inhibitory neurotransmitter in the vertebrate brain. It interacts with three kinds of receptors: Class A1, B2 and C3. While GABAAR and GABACR are ligand-gated Cl– channels, GABABR can activate other channels via G protein.
The binding of GABA transmitter to the GABAAR opens the Cl– channels which leads to an increase in membrane conductance and an inhibition of neuronal activity.
The GABAAR is composed of 6 subunits: α, β, γ, ε and π4. Each one is encoded by a few genes. There are 6 different genes for the α subunit, 3 for β and γ, and 1 for the others. In most cases, the receptor is assembled to a pentamer5 of 2α, 2β and 1γ subunit when each one consists of 4 putative transmembrane domains, with a long N-terminus and a short C-terminus tail, both extracellular.
The inhibition mediated by GABA is also induced when other agents interact with GABAAR.
The receptor possesses modulatory binding sites for antiepileptic drugs, anxiolitics6 sedative and anesthetic agents and this makes it a study of therapeutic importance.
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