Benzodiazepine binding site on GABA receptors is on ?

[Ref: Goodman/Gillman REF : katzung pharmacology : 14th ed The exact subunit structures of native GABA receptors are still are unknown, but it is thought that most GABA receptor are composed of alpha, beta & gamma subunits that Coassemble with some unceain stoichiometry. Binding site of GABA is on beta-subunit. Benzodiazepine site is located on the a subunit but the stabilization or completion of that site in the assembled. Structure also requires the y subunit.