Molecular dissection of benzodiazepine binding and allosteric coupling using chimeric gamma-aminobutyric acidA receptor subunits. Molecular Pharmacology 53

Although g-aminobutyric acid (GABA)A receptor a subunits are important for benzodiazepine (BZD) binding and GABA-current potentiation by BZDs, the presence of a g subunit is required for high affinity BZD effects. To determine which regions unique to the g2S subunit confer BZD binding and potentiation, we generated chimeric protein combinations of rat g2S and a1 subunits using a modified protocol to target crossover events to the amino-terminal extracellular region of the subunits. Sev-eral chimeras with full open reading frames were constructed and placed into vectors for either voltage-clamp experiments in Xenopus laevis oocytes or radioligand binding experiments in human embryonic kidney 293 cells. Chimeras (x) containing at least the amino-terminal 161 amino acids of g2S bound BZDs with wild-type affinity when coexpressed with a1 and b2 sub