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 β2 isoform is a 55 kDa, 450 amino acid (aa), 4 transmembrane protein with two terminal extracellular regions. The ligand-binding region is in the N-terminus (aa 13 - 218). The β2 subunit is part of the most common GABA A receptor combination in the mammalian brain (α1β2γ2). Like the other two beta subunits, beta 2 is phosphorylated on a consensus phosphorylation site (S410 of the precursor) that exists in the second cytoplasmic domain. In contrast to the other beta subunits, only PKC is capable of this modification. However, tyrosine phosphorylation of beta 2 is known, and this apparently increases GABA A current amplitude.