FIGURE 3.

Patch clamp recordings of xASIC1 and mutant xASIC1-SQL. A, currents from wild type xASIC1.1 evoked by the indicated concentrations of protons recorded from a patch in the outside configuration. Protocol was as follows: 4 s of pH 8.0 followed by 8 s of activating pH. The arrow marks the initiation of stimulus. The patch contains ∼400 channels. B, currents from xASIC1.1-SQL. Protocol was as follows: 8 s of pH 8.0 and 12 s activating pH. C, currents from patches containing xASIC1 channels activated by low concentrations of protons to observe single channel events. At pH 7.3, individual openings are evident. D, currents from patches containing xASIC1-SQL. WT, wild type.