Biochemical and immunological similarity of soluble angiotensin II-binding proteins in different organs.

Binding of angiotensin II has been detected in soluble extracts of rabbit liver, adrenal gland, aorta, brain, kidney and uterus. In each case, binding required p-chloromercuriphenylsulfonic acid and bound angiotensin II was released by treatment with dithiothreitol. These properties resemble those of the 75 kDa binding protein purified from liver. Immobilized guinea pig antiserum developed against the isolated hepatic protein removed binding activities from the different extracts in an immune-specific, quantitatively comparable manner. In addition, the activities were removed by a mouse monoclonal antibody which specifically recognized a protein of 75 kDa in the various preparations. An immunologically homologous angiotensin II-binding protein with similar characteristics was also identified in the soluble fraction of rat liver.