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An amino acid (γ-aminobutyric acid) that is a very important inhibitory neurotransmitter in the central nervous system and retina (and also in many invertebrates). The GABA receptor is one of a family of neurotransmitter receptors that includes the glycine receptor and the nicotinic acetylcholine receptor and is the target for a variety of drugs. There are two main classes, ionotropic (GABAA and GABAC receptors) and metabotropic (GABAB receptor). The GABAA receptor is a ligand-gated chloride channel specifically blocked by bicuculline and picrotoxin, a hetero-oligomer with (probably) five subunits, generally two pairs of α and β subunits and a γ subunit, probably arranged as a tight group with the chloride channel in the centre. The α and γ chains are needed for binding of benzodiazepine and the β chains bind GABA. Phosphorylation will alter the receptor's properties. The metabotropic GABAB receptor is a G-protein-coupled receptor found in the brain and is negatively coupled to adenylate cyclase through a Go protein and thus acts indirectly on N-type calcium channels reducing catecholamine release. The GABAC receptor resembles GABAA but is restricted to the retina.

Subjects: Chemistry — Medicine and Health.

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