We also observe high contributions from Glu-364 (-7.104 MV/cm) and Glu-930 (-7.323 MV/cm). These residues are part of an outer ring of carboxylates that was reported to act in concert with the selectivity filter to discriminate Na + . In Na v 1.7, this ring contains three, and not four, carboxylate residues: two Glu from DI and DII and one Asp from DIV. Indeed, while other Na v s complete this outer ring with an Asp in DIII, Na v 1.7 contains Ile at that position.