Functional reconstitution of a GABAA receptor purified from bovine brain.

The GABAA/benzodiazepine receptor has been solubilized from bovine brain membranes and purified by benzodiazepine affinity chromatography. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed two major protein species of 53 and 56 kDa. The purified protein has been reconstituted, in a functionally active form, into phospholipid vesicles. Chloride flux responses of the reconstituted preparations were investigated in stopped-flow experiments by monitoring fluorescence changes of a chloride-sensitive dye trapped within the vesicles. Flux was rapidly stimulated by muscimol and this response was potentiated by diazepam and blocked by desensitization of the receptor and by preincubation with the channel blocker, picrotoxin.