Renin is a highly specific endopeptidase, related to pepsin, whose only known function is to generate angiotensin I from angiotensinogen in the plasma, initiating a cascade of reactions that produce an elevation of blood pressure and increased sodium retention by the kidney. Cleavage of Leu-|-Xaa bond in angiotensinogen to generate angiotensin I. Dimer of a heavy chain and a light chain joined by a disulfide bond. Submandibular gland. Present as a single-copy gene in strains such as BALB/c and C57BL/6 while some strains such as Swiss and Akr contain two copies. The active enzyme isolated from the submandibular gland has catalytic and antigenic activities similar to renal renin. Belongs to the peptidase A1 family.