Angiotensinogen is a serum alfa-2-globulin which is secreted in the liver and released into the blood circulation. Angiotensinogen is a member of the serpin family. It is not known whether it inhibits other enzymes, unlike most serpins. On hydrolysis by renin, angiotensinogen gives rise to angiotensin. Plasma angiotensinogen levels are increased by plasma corticosteroid, estrogen, thyroid hormone, and angiotensin II levels.
Also known as renin substrate, angiotensinogen is A 60 kD glycoprotein of the alfa-2-globulin fraction of plasma proteins, which is synthesized and released from the liver. It is cleaved in the circulation to form the biologically inactive, angiotensin I, a decapeptide split from the N-terminal by renin, a proteolytic enzyme.
Human angiotensinogen is 452 amino acids long, but other species have angiotensinogen of varying sizes. The first 12 amino acids are the most important for activity.