Abstract
Irreversible labeling of benzodiazepine receptors in membranes from cerebellum or hippocampus was compared at 0°C or 37°C using [3H]flunitrazepam as a photoaffinity ligand. [3H]Flunitrazepam reproducibly and irreversibly labeled mainly one protein (P51) in cerebellum and at least two proteins (P51 and P55) in hippocampus at both temperatures. Differential inhibition at 37°C of irreversible [3H]flunitrazepam binding to the individual proteins by several selective benzodiazepine receptor ligands supports the hypothesis that P51 and P55 are associated with different benzodiazepine receptors.