Molecular mechanisms of peripheral benzodiazepine receptors.

Peripheral-type benzodiazepine receptors were identified initially as binding sites in peripheral tissues with markedly different drug specificity than the central type receptors. The density of peripheral receptors varies greatly among tissues with selective localization within organs. Steroid producing areas of glands, such as the adrenal, testes and ovary, are highly enriched in these receptors. Intracellular localizations provide further insight into function with peripheral receptors largely if not exclusively associated with outer membranes of mitochondria. Purification of the peripheral receptor protein from rat kidney mitochondria reveals two apparent subunits with molecular weights of about 30 and 18 kD respectively. This complex is functionally intact as determined by its ability to reversibly bind PK-11195, Ro5-4864, and PK-14105 with high affinity and specificity.