FIGURE 11.

ENaC is markedly activated by subtilisin cleavage of α lacking the tract between the two furin cleavage sites. Electrophysiological data correspond to the biochemical data summarized in Fig. 10. Spontaneous activity of αFD was significantly lower than that of αWT but higher than that of αFM (see Fig. 6C). Channels formed with either αWT or αFD were activated to similar levels after 50 ng/ml subtilisin (N.S. indicates p > 0.05). Channels formed with αLD exhibited low activity due to the absence of cleavage as well as its decreased plasma membrane levels (see Fig. 10). Subtilisin was without effect on channels containing αLD. Note the difference in the y axis between αWT/αFD and αLD. n = 12, 14, and 8 from 5 different frogs for αWT, αFD, and αLD, respectively. See “Results” for additional details.