<prompt> Benzodiazepine binding ste on GABA receptors is on-g-subunita-subunitb-subunitd-subunit  <response>: Ans. is b i.e., a-subunit o The exact subunit structures of native GABA receptors are still are unknown, but it is thought that most GABA receptor are composed of a, b and g subunits that Coassemble with some uncertain stoichiometryo Binding site of GABA is on b-subunit.o Benzodiazepine site is located on the a subunit but the stabilization or completion of that site in the assembled structure also requires the g subunit.The photo-affinity labelling of the benzodiazepine site has confirmed, using isoform - antibodies, to be on an a and not a g subunit. -- Receptor subunit complexes.o So, BZD binding site is present on a subunit at a - g interface, and both a g units are required for BZDs action.o Barbiturates act on picrotoxin site that is located usually on b - subunit at a- b interface. Both a b subunit are required for barbiturates action.o GABA - b - subunito BZD - a subunit at a - g interface, i.e. ag siteo Barbiturate - b subunit at a- b interface, i.e. ab site 