FIGURE 5.

Selectivity of ASIC1a mutants toward alkali metals. The symbols represent relative permeability toward alkali metals of C70L channels (black circles), G438C (white circles), and G438A channels (gray circles). Whole-cell currents were elicited by a change in extracellular pH from 8.0 to 5.0 with solutions containing Na⁺, Li⁺, K⁺, Rb⁺, or Cs⁺ as the main permeable cations. The peak current evoked by extracellular acidification with a defined alkali metal as the main permeable cation was normalized to the peak current evoked by extracellular acidification with Na⁺ as the main permeable cation. The relative permeability (X⁺/Na⁺) is plotted as a function of the diameter of the nonhydrated cations (n = 8–15).