Fig. 4.

The 397–426 interaction determines prominence of F427 within lumen. (a Upper) Overview of MTS-ET experiments. Once PA₆₃ channels, containing the F427C mutation have reached steady state, g_initial, MTS-ET is added to the trans compartment to a final concentration of 20 μg/ml. Channel conductance falls to a new steady state, g_final, and the percent block (g block) is calculated by using (g_initial – g_final)/g_initial. (a Lower) The percent reduction of macroscopic conductance for K/D, Q/D, and Q/Q pores with F427C (n = 3–6). (b) Intersubunit loop interactions cause a pore constriction that brings F427 more prominently into the pore.