GABA A (γ-aminobutyric acid-type A) receptors are members of the cysteine-loop family of neurotransmitter-gated ion channels. GABA binding to A-type receptors induces anion-selective ion channel opening. These receptors are the principal fast inhibitory neurotransmitter receptors in the CNS. GABA A receptors are heteropentamer combinations of seven subunit types; α, β, γ, δ, ε, θ, and π. Three subunits, α, β, and γ, have at least three separate gene products in mammals, and typical GABA A receptors have some combination of α, β, and γ subunits.
The rat α1 isoform is a 50 - 52 kDa, 428 amino acid (aa), 4 transmembrane protein with two terminal extracellular regions. The ligand-binding region is in the N-terminus (aa 15 - 222). As with many receptors, phosphorylation of GABA A R is used as a regulatory mechanism. CaM kinase II is known to phosphorylate the a1 GABA A subunit and regulate benzodiazepine binding. The α1 subunits are particularly abundant in the cerebellum and may contribute to GABA receptor distribution. In the hippocampus and amygdala, the α1 GABA A subunit may contribute to amnesia.
