Fig. 2.

Characterization of functional EC domain chimeras. (A) Protein isolation using cell surface biotinylation in intact cells and analysis by SDS-PAGE, immunoblots of protein prior to isolation of biotinylated proteins, and (B) purified biotinylated proteins using streptavidin agarose beads. (C) Currents evoked by a pH 4 stimulus were of significantly larger magnitude in AB5-transfected cells than those transfected by ASIC2a; both AB4.1 and AB11-5 produced significantly smaller currents than ASIC2a. (D) The inactivation time constant was not significantly different between ASIC2a, AB5, AB4.1, and AB11-5. (E and F) pH-response curves were evoked by applying pH stimuli in a random order, as shown by the example ASIC2a trace; the EC₅₀ for AB4.1 was significantly shifted to the right compared with ASIC2a. (G and H) SSI curves were evoked by stimulating with a pH 4 stimulus every minute, with the bath solution becoming ever more acidic between stimuli, as indicated in the example ASIC2a trace; the AB5 SSI curve was significantly shifted to the left compared with ASIC2a. *P < 0.05, **P < 0.005, ****P < 0.0001.