PURIFICATION OF THE GAMMA-AMINOBUTYRIC ACIDA/BENZODIAZEPINE RECEPTOR COMPLEX BY IMMUNOAFFINITY CHROMATOGRAPHY

The bovine gamma-aminobutyric acid(A)/benzodiazepine receptor complex has been purified by a novel immunoaffinity chromatography method on immobilized monoclonal antibody 62-3G1. Immunopurification of the complex was achieved in a single step with an improved yield over affinity chromatography on the benzodiazepine Ro 7-1986/1. High-resolution sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the immunoaffinity-purified receptor revealed three major peptide bands of 51,000, 55,000, and 57,000 M(r) which were also present in the Ro 7-1986/1 affinity-purified receptor. Peptide mapping, immunoblotting with subunit specific antibodies, and photoaffinity labeling with [H-3]flunitrazepam and [H-3]muscimol have been used for the identification of receptor subunits, including several which comigrated in a single band in SDS-PAGE.