Figure 2. Plasmin in the renal tubule can aberrantly cleave and activate ENaC.
Plasminogen is absent in the urine of normal rats or humans, but is present in the setting of nephrotic syndrome (20, 21, 56, 57). It is likely that secreted tubular urokinase generates active plasmin from plasminogen, and that plasmin cleaves the γ subunit distal to the furin cleavage site to release the γ inhibitory peptide (**) (20, 21, 58-60). The α inhibitory peptide (*) is already released by furin cleavage at two sites (44, 51). This figure is adapted from Eaton, DC and Pooler, JP (61).