DISTINCT LOCALIZATION OF RENIN AND ANGIOTENSINS IN SEPARATE SUBCELLULAR-FRACTIONS OF THE RAT ADRENAL-CORTEX

The subcellular localization of renin and immunoreactive angiotensins I and II was studied in rat adrenal cortical tissues. The identity of the immunoreactive angiotensins was confirmed as angiotensin I and ang iotensin II by radioimmunoassay and high-performance liquid chromatogr aphy, respectively, with reference to standard compounds. By different ial centrifugation of tissue homogenate in 0.25 M sucrose/30 mM Tris-H Cl/l mM EDTA, pH 7.4, specific immunoreactive renin was found to be lo calized principally (60%) in the mitochondrial fraction (P2), whereas about 40% of both angiotensins I and II was contained in the soluble f raction; only 18-20% of both peptides was contained in the P2 fraction . On Percoll density gradient centrifugation of P2, renin was fraction ated mostly in a denser band whereas angiotensins I and II were contai ned in a lighter density area closely corresponding to mitochondrial a nd lysosomal marker enzymes. These results suggest that renin and angi otensins in the cells of the rat adrenal gland reside in different sub cellular compartments and argue against intracellular formation of ang iotensins by renin in renin granules.