Isolation of a GABA receptor from bovine brain using a benzodiazepine affinity column

Benzodiazepine receptor solubilized from bovine cortical membranes was bound to a new benzodiazepine affinity column, the synthesis of which is described. Bio‐specific elution with the benzodiazepine compound chlorazepate resulted in the elution of fractions highly enriched in specific binding for the GABA receptor agonist muscimol. Specific activity for [ 3 H]muscimol binding was >1.3 nmol/mg protein. It is shown that [ 3 H]flunitrazepam binding activity can be recovered by removal of chlorazepate from the purified fraction. These results strongly support a model which suggests that the 2 binding sites reside on the same physical entity.