Properties of Renin-Binding Protein

Hog renal renin-binding protein could bind homologous and non-homologous renin but could not bind human renal renin. Renin-binding protein was only detected in the kidney and pituitary in which renin is found in relatively high concentration. The renal binding protein had no interaction with renal acid proteases nor with extrarenal renins obtained from pituitary and submaxillary glands, indicating that the binding is specific for renal renin. Subcellular localization of the binding protein was studied using rat kidney by differential and density gradient centrifugation. Most renin-binding protein was recovered in the cytosol fraction and was not associated with sedimentable subcellular organelles. A renin-secreting tumor (Juxtaglomerular cell tumor) in human kidney produced not only renin but also renin-binding protein in a very large quantity.