Fig. 1
From: GABAA receptors: structure, function, pharmacology, and related disorders
Schematic representation of GABAA receptor structure. (A) GABAA receptors are heteropentamers that form a chloride-ion-permeable channel. They are formed by 19 subunits: α1–6, β1–3, γ1–3, δ, ε, θ, π, and ρ1–3. The GABA binding sites are located at the junction of β+/α−, whereas benzodiazepines (BZs) are located at α+/γ− interface. Anesthetics are located at different sites where barbiturates bind to α+/β−, and γ+/β− interfaces while etomidate binds to β+/α− interface. The binding site of the neurosteroids is located at α subunit as well as the β+/α− interface. (B) The most popular GABAAR isoform is composed of α1, β2, and γ2 subunits arranged γ2β2α1β2α1 counterclockwise around the central pore. (C) The mature subunit contains a large hydrophilic extracellular N-terminal, four hydrophobic transmembrane domains (TMD: TM1–TM4), and a small extracellular C terminus. TM1 and TM2 are connected by a short intracellular loop while a short extracellular loop connects TM2 and TM3. Besides, TM3 and TM4 are connected by a lengthy intracellular loop that can be phosphorylated