gamma-Aminobutyric acid/benzodiazepine receptor protein carries binding sites for both ligands on both two major peptide subunits.
Affinity column-purified GABA-benzodiazepine receptor proteins from human, cow, and rat brain were photoaffinity labeled with both [3H]flunitrazepam and [3H]muscimol and examined by gel electrophoresis in sodium dodecyl sulfate. Using high receptor protein concentrations (1 microM), the benzodiazepine ligand [3H]flunitrazepam was incorporated covalently primarily into the expected 52 kiloDalton major subunit but also significantly into a second 57 kiloDalton peptide. Likewise the GABA ligand [3H]muscimol photolabeled primarily the 57 kiloDalton peptide but also to some extent the 52 kiloDalton peptide. This cross-labeling suggests strongly that both major subunits carry binding sites for both GABA and benzodiazepine.
Bureau
M
M
Department of Pharmacology, School of Medicine, University of California, Los Angeles 90024.
Olsen
R W
RW
D000345:Affinity Labels / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D005445:Flunitrazepam / Q000378:metabolism*; D006801:Humans; D008024:Ligands / Q000378:metabolism; D046911:Macromolecular Substances; D008970:Molecular Weight; D009118:Muscimol / Q000378:metabolism*; D010777:Photochemistry; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism*
D000345:Affinity Labels; D008024:Ligands; D046911:Macromolecular Substances; D011963:Receptors, GABA-A; D009118:Muscimol; D005445:Flunitrazepam