GABAA receptors are composed of five protein subunits that can belong to different subunit classes. There are 19 genes for GABAA-R subunits (Simon et al., 2004). These include 16 subunits (α1–6, β1–3, γ1–3, δ, ε, θ, π) combined as GABAA, and 3 rho (ρ) subunits, which contribute to what have sometimes been called GABAC receptors; the latter are considered by the Nomenclature Committee of IUPHAR to be subtypes of GABAA-R containing the ρ subunits, and they recommend against using the term ‘GABAC receptors’, especially in the title, abstract, or initial mention of these receptors in publications (Barnard et al., 1998; Olsen & Sieghart, 2008).
