Immunohistochemical localization of adrenodoxin and adrenodoxin reductase in bovine adrenal cortex.

The zonal distribution of adrenodoxin and adrenodoxin reductase (EC 1.6.7.1) in the bovine adrenal cortex as well as their intracellular localization has been studied by the direct method of peroxidase-labelled antibody (Fab' or F(ab')2 fraction) technique. The results indicated that both proteins localized mainly in zonae fasciculata and reticularis whereas very few were present in the zona glomerulosa. Only parenchymal cells in the adrenal cortex were proved to contain both proteins. The intracellular localization of both adrenodoxin and the reductase was demonstrated to be exclusively on the inner membrane of mitochondria of these parenchymal cells by immunoelectron microscopy. The validity of the immunocytochemical method employed in this study to determine the fine localization of both proteins in the mitochondria as well as the significance of the zonal distribution in relation to the function of each individual zone is discussed.