Association of proteins irreversibly labeled by 3H-flunitrazepam with different benzodiazepine.

Studies of the regional distribution of proteins irreversibly labeled by 3H-flunitrazepam indicate that the contribution of the individual proteins to total irreversible binding of 3H-flunitrazepam was different in different brain regions and varied independently from each other. Study of the inhibition by Cl 218 872 of 3H-flunitrazepam binding to the individual benzodiazepine binding proteins in cerebellum and hippocampus revealed that inhibition by Cl 218 872 of total irreversible binding of 3H-flunitrazepam to proteins was closely similar to that of reversible binding to membranes. However, when inhibition by Cl 218 872 of 3H-flunitrazepam binding to individual benzodiazepine binding proteins was measured, it was found that this substance had different affinity for the various individual proteins. The present results are consistent with the hypothesis that the protein P51 is associated with the BZ1-benzodiazepine receptor subtype and that the individual proteins irreversibly labeled by 3H-flunitrazepam are independent from each other and associated with different benzodiazepine receptors.