Fig. 7.
Proteolysis of native ENaC proteins by uPA. A: characterization of a new polyclonal antibody against the COOH-terminal peptide of rat γ ENaC. Both total (γFLAGT) and biotinylated plasma membrane proteins (γFLAGM) from Xenopus oocytes expressing heterologous mouse ENaC with FLAG attached to the NH2-terminal tail were used as positive controls (lanes 1 to 3) for mouse lung tissues (MLT, lane 4) of WT C57 strain. The blots were probed with either monoclonal anti-FLAG antibody (FLAG) or polyclonal antibody against the COOH-terminal tail of rat γ ENaC (rCG). White lines at the left side of the blot are markers. Arrows indicate the size of proteins. B: comparison of lung γ ENaC proteins between WT and uPA knockout (KO) mice. Top blot is for γ ENaC and bottom one is for β-actin. C: quantitative densitometry of cleaved band normalized to β-actin. N = 3 independent experiments, *P < 0.05 vs. WT.