The GABA A receptor is a heteropentameric glycoprotein. A total of 5 distinct polypeptide subunits have been cloned to date; a, b, g, d and r, and multiple isoforms of these subunits are reported in the literature. Different confirmations of the GABA-A receptor are found throughout the brain, and the most common mammalian arrangements of sub-units is (a1)2(b2)2(g1). The specific subunits in the GABA-A receptor confer functional diversity on the receptor. For example, the g subunit needs to be co-expressed with the a and b sub-units to observe the potentiation of the GABA A receptor by benzodiazepines.
GABA is the major inhibitory neurotransmitter in the central nervous system. The GABA A receptor is composed of five sub-units – two alpha, two beta and one gamma sub-unit. Two molecules of GABA activate the receptor by binding to the alpha sub-units. Once activated the receptor allows the passage of negatively charged ions into the cytoplasm, which results in hyperpolarization and the inhibition of neurotransmission.