Abstract: The present invention relates to a corin polypeptide which contains one or more frizzled corin and possesses various activities, including, e.g., serin protease activity and a pro-ANF converting activity, LDLR, SRCR repeats, serine protease catalytic domains such as human and mouse corin. The invention further relates to methods of using such nucleic acids and polypeptides in therapeutics, diagnostics, and research. For example, the nucleic acids and polypeptides of corin can be utilized in methods to identify modulators of its activity, in animal models to mimic human disease, and to treat kidney, cardiovascular, and other conditions in which corin is involved.