1. Poly(A) + mRNA from mouse submaxillary gland encodes a polypeptide of molecular weight 48 000 (48K polypeptide) which is abundant in the male. 2. This polypeptide is selectively absent in the translation products of mRNA from a strain of genetically renin-deficient mice C57 BL/10J. 3. The 48K polypeptide binds and co-elutes in identical fashion with pure authentic renin on pepstatin affinity chromatography. 4. Immunoprecipitation of translation products of male glandular mRNA with renin-specific antibody yielded this 48K band upon analysis by SDS/polyacrylamide gel electrophoresis and fluorography. Pure renin of molecular weight 37 000 blocked the binding of this polypeptide to antirenin antibody. 5. Mouse submaxillary gland synthesizes a renin precursor. The renin mRNA is androgenically regulated.
1. The major angiotensin I-generating activity of rat brain extracts has a pH optimum different from that of renal renin and is not inhibited by renin specific antibody. 2. Affinity chromatography utilizing renin specific antibody, pepstatin and α-casein yielded fractions that resembled renal renin more closely with respect to antibody inhibition and pH optimum as well as an absence of the ability to hydrolyse haemoglobin. 3. We conclude that rat brain contains a host of enzymes with angiotensin I-generating activity including acid and neutral proteases and an enzyme with the immunochemical identity of renal renin. The biosynthetic origins of this renin-like protein remain uncertain.