Figure 6.

Monofunctional MTS-2 protects mutant channels but not wildtype channels from bifunctional MTS-2-MTS. Mutant or wildtype γ subunits were co-expressed with wildtype α and β ENaC subunits in Xenopus oocytes. A, ENaC currents were measured using two-electrode voltage clamp at −100 mV. Oocytes were mock-treated or treated with 10 μm MTS-2 for 60 s followed by washout with 110-Na buffer for 60 s. Oocytes were then treated with 10 μm MTS-2-MTS for 60 s followed by washout with 110-Na buffer for 60 s. B, the effect of MTS-2-MTS treatment after mock or MTS-2 treatment was determined by comparing current after washout of MTS-2-MTS with current just before MTS-2-MTS addition. Bars, mean. **, p < 0.01; ****, p < 0.0001, by Student's t test.