FIGURE 5.

V23C shows gating-dependent spontaneous activity when modified by MTSET placed on the periplasmic, but not cytoplasmic side. Channel traces of untreated (top) and treated (bottom) patches containing native membranes expressing V23A. In the bottom trace, treatment was effected by filling the pipette with MTSET-containing buffer. No channel activity is initially observed (left part of both traces), but can be induced by suction in the pipette (pressure is shown below each channel trace). In both traces MscS activity (indicated by *) and MscL activity (indicated by ∇) are observed (MscL rides up upon the MscS activity in the top trace). Note that in the bottom trace, subsequent to pressure-induced gating, a “flickery” channel with extremely short open dwell times is observed; this is shown in the bottom trace, which is a blowup of the indicated region. Hash marks represent ∼3–5 min removed to show durability of response.