FIGURE 7.

Amino acid sequence alignment of receptor site 4 on sodium channel isoforms. A, crucial determinants of neurotoxin receptor site 4 shown are located at the S3-S4 linker of sodium channel domain II. The positions of amino acids of interest are shaded in gray. Nav1.1-1.4 and Nav1.8 channels are from rat (r), and Nav1.5-1.7 channels are from human (h). B, schematic diagram of sodium channel α subunit. The voltage sensor (segment 4) of each domain is shaded in gray and marked with “++.” The sequences of the S3-S4 linker of domain II is indicated in A. Nav1.9 is not shown as the IIS3-S4 linker is longer and completely divergent.