[3H]Muscimol Binding Site on Purified Benzodiazepine Receptor

Abstract

The presence of a [³H]muscimol binding site on the purified benzodiazepine receptor was demonstrated. The purified protein was apparently homogeneous as shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis (stained with silver), with a molecular weight of 60,000 ± 3000. The benzodiazepine binding sites were characterized as being of the central type and the [³H]flunitrazepam binding was enhanced by GABA. This activation was antagonized by bicuculline. [³H]Muscimol specifically binds to the benzodiazepine receptor. The Scatchard plot indicates a K_d of 23 nM and the ratio [³H]flunitrazepam/[³H]muscimol is approximately unity.