e is that, at variance with other aspartic proteases such as pepsin or cathepsin D, renin is fully specific for angiotensinogen.Structure and activity of proreninProrenin, the inactive precursor of renin, is a pre-hormone synthesized in adrenals, retina, ovaries, and testis (Danser et al 1989; Sealey et al 1988; Itskovitz et al 1992; Clausmeyer et al 1999).