FIGURE 1.

Reverse pH dependence of Kir6.2(F168E) channels. A, structure of the KirBac1.1 channel, with bundle crossing residue Phe-146 highlighted in red. B, alignment of multiple Kir channel M2 segments. The first amino acid corresponds to the putative “glycine hinge” residue. The highlighted position corresponds to the aromatic bundle crossing residue depicted in A. C and D, continuous inside-out patch clamp recordings of WT Kir6.2 and Kir6.2(F168E) (both coexpressed with SUR1 in COSm6 cells), respectively, with internal pH changes as indicated. A small concentration of Ba²⁺ was included in solutions to assess leak with brief pulses to +50 mV.