Alignment of the amino acid sequences in transmembrane domain 2 (TM2).

<p>Residues that line the pore in most Cys-loop receptors are shown in red. Arginine in position 0’ is critical for Cl-selective channels. The equivalent position for cation selective channels (-1’) generally has negatively charged residue (E or D). Note that the two isomers of <i>C</i>. <i>salei</i> nACh1 have a positively charged amino acid in this location. Position 13’, which is occupied by hydrophobic residues in cation permeable channels, is shown in green. Sequences were aligned with MAFFT.