ABSTRACT
Angiotensinogen is a 55,000- to 60,000-Da glycoprotein that is moderately abundant in blood and cerebrospinal fluid. The amino-terminal decapeptide of angiotensinogen, angiotensin I, is released by the action of renin and angiotensinogen is the only known naturally occurring renin substrate. Angiotensinogen is synthesized by a variety of cell types, most prominently hepatocytes, adipocytes, and astrocytes. The detection of angiotensinogen mRNA in liver confirmed earlier studies showing renin substrate release from perfused liver and dispersed hepatocytes. Immunohistochemical localization of hepatic angiotensinogen revealed diffuse cytoplasmic immuno-deposits in periportal hepatocytes consistent with a presence in the Golgi apparatus and rough endoplasmic reticulum. The angiotensinogen gene is single copy and has been isolated from rat, in which it has been mapped to chromosome 19, from mouse, and from human. The rat gene remains the most thoroughly characterized, but the structure and function of the mouse and human genes are not significantly different.
