Renin, a proteolytic enzyme formed in the granules of the juxtaglomerular apparatus cells, catalyzes conversion of the protein angiotensinogen to angiotensin I, a decapeptide.

小球旁体细胞颗粒内形成的一蛋白水解酶，催化蛋白血管紧张换为血管紧张Ⅰ，即十肽。