Subcellular distribution and binding characterization of the peripheral benzodiazepine receptor in the rat liver

Abstract

The peripheral benzodiazepine receptor (PBZ) population in the rat liver has been kinetically and pharmacologically characterized. These data revealed a receptor with a dissociation constant (Kd) of 5.67 nM and a receptor density of 758 fmoles/ mg protein in a crude membrane preparation. Subcellular distribution studies demonstrated that PBZs were detected in highly purified nuclear, mitochondrial and microsomal fractions. Porphyrins were shown to interact at the PBZ with protoporphyrin IX and hemin having the highest affinity. Preliminary studies on the subnuclear distribution of PBZs are reported. In summary, the study has (1) characterized liver PBZs, (2) shown the subcellular distribution of these receptors and (3) pharmacologically characterized nuclear, mitochondrial and microsomal PBZs in the liver.