Editorial Commentary Is (Pro)Renin Receptor a Multifunctional Receptor?

The existence of various components of the renin-angio-tensin system in the eye has been known for more than a decade, and the importance of this system in ocular patho-physiology is a subject of active investigation.1 It has long been recognized that prorenin, an inactive precursor of renin, is elevated in the ocular fluids of patients with diabetic retinopathy.2 However, the pathophysiological implications of these elevated levels remained a mystery until the discov-ery of a specific receptor for renin and prorenin: the (pro)re-nin receptor [(P)RR].3 (P)RR is a 350–amino acid transmembrane protein which has been proposed to function by two distinct mechanisms: (1) by binding to (pro)renin, (P)RR activates renin’s enzy-matic activity inherent in prorenin, leading to the generation of angiotensin II by a traditional renin-angiotensin system pathway at the cell/tissue level4; and (2) (pro)renin binding t