Fig. 1.

Conversion of a lamprey acid-sensing ion channel (ASIC) into a proton-activated channel. A: alignment of the amino acid sequences of rat and lamprey corresponding to transmembrane segment 1 (TM1), the β1-strand, a linker between β1 and β2 according to the crystal structure of chicken ASIC1. Underlined are residues that when substituted for the corresponding ones in rat produced functional channels with properties similar to rat ASIC1. B: representative current evoked by pH 6.0 from functional lamprey with two mutations, Q77L, T85L (2M); and three mutations, C73H, Q77L, T85L (3M). C: Western blot showing surface expression of wild-type (WT) and mutant channels with one (1M = Q77L), two (2M = Q77L, T85L), or the three substitutions (3M = C73H, Q77L, T85L) probed with FLAG monoclonal.