Renin(redirected from big renin)
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a proteolytic enzyme in vertebrates and humans. It is produced by specialized cells in the arteriole walls of renal glomeruli, from where it passes into the blood and lymph. Renin is one of the enzymes in the renin-angiotensin system. It acts on the specific glycoprotein angiotensinogen by breaking the bond between two leucine radicals. The resultant inactive decapeptide (angiotensin I) is enzymatically converted into the active hormone angiotensin II (hypertensin, or angiotonin). Enzymes resembling renin are found in the uterus, placenta, salivary glands, brain, and the walls of certain major arteries.