Figure 2.
pH titration suggests formation of Glu-138–Arg-148 salt bridges. (a) The carboxyl group of Glu-138 and the guanido group of Arg-148 are proposed to form a salt bridge, which involves both short range electrostatic attraction and hydrogen bonding. (b) Effect of external pH on whole-cell current produced by the wild-type IRK1 channel, recorded by two-electrode voltage-clamp. Each data point is an average of 5–8 measurements. Solid line represents a least-squares fit to the Hill equation with a pKa of 1.97 and a Hill coefficient of 4.1.