Characterization of functional chimeras with changes in the N-terminus. (A) AB6 consisted of ASIC2a with the addition of the 51-amino-acid–long novel N-terminus of ASIC2b, and AB5-N was constructed from AB5 by exchanging the 42 amino acids prior to the first TM domain. Both chimeras responded to pH 4 with ASIC-like currents. (B) AB5-N produced significantly smaller currents than ASIC2a at pH 4, whereas currents of AB6 did not differ from ASIC2a. (C) Inactivation time constant was significantly slower in AB6, but faster for AB5-N compared with ASIC2a. (D) pH-response curve of AB6 was significantly shifted to the right compared with ASIC2a. (E) SSI curve of AB6 was significantly shifted to the left compared with ASIC2a. *P < 0.05, **P < 0.005, ****P < 0.0001.