Figure 9.

MTS-rhodamine permeates and blocks the open P2X7[G345C] pore. A, Structure of MTS-rhodamine shown in two-dimensional (left) and three-dimensional (right) representations. B, MTS-rhodamine (3 μm, blue bar) strongly inhibits the current evoked by ATP (3 mm, 30 s) in G345C cells when applied to the open channel (i.e., during ATP application). It has no effect on currents evoked by ATP (3 mm, 30 s) in wild-type cells. C, MTS-rhodamine (3 μm, blue bar) did not alter currents evoked by ATP (3 mm, 5 s) when applied to the closed channel (i.e., between ATP applications) in cells expressing G345C or wild-type receptors.