The (pro)renin receptor was first identified as a 350-amino acid protein with a single transmembrane domain. This receptor binds to prorenin to mediate its dual functions: activation of ERK1/2 independently from angiotensin II generation and induction of full enzymatic activity to initiate angiotensin II-dependent effects. (Pro) renin receptor has recently been shown to undergo intracellular processing, such that it exists in three different molecular forms. These include the full-length (pro)renin receptor, truncated amino-terminal soluble fragment, and carboxy-terminal fragment containing an accessory protein of the vacuolar-type H(+)-ATPase. Their exact distributions and existing molecular forms remain to be determined.