Association of Proteins Irreversibly Labeled by ³H-Flunitrazepam with Different Benzodiazepine Receptors

Summary

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.