2nd- and 3rd-order coupling free energies between the upper interface residues of the Shaker Kv channel during activation gating.

i,j) residue pairs, as indicated in Figs. 4B–E, was measured in the presence (Δ2G(i,j)) or absence (Δ2G (i,j)/k) of the native third k position.a The coupling free energy of the (k on the (i,j) interaction pair is (Δ3G(i,j)k), calculated by subtracting the free energies of coupling in the presence or absence of the native third k position. Considering the symmetry of the three-dimensional mutant construct (see Fig. 5), any of the three residue combinations yields a similar value for Δ3G(i,j)k.b The effect of residue Δ2G(i,j) coupling value between the indicated pair where both T248 and Y415 residues are in the same subunit.c Shown in parenthesis is the