Fig. 3: Potential gating residues in hNKCC1 and mKCC2.

a The amino group of R307 of TM1b interacts with the carbonyl oxygen of E389 from TM3 to constrict the extracellular gate of hNKCC1. b hNKCC1 transport activity is greatly decreased by mutation of the extracellular gating amino acids E389, R307, and L671; mean ± SEM. c At the intracellular end of the hNKCC1 translocation pore, R358 of ICL1 interacts with D632 of the neighboring TM8. d hNKCC1 transport activity between WT and mutants in the intracellular essential amino acids (R358 and D632); mean ± SEM. e hNKCC1 mutants of D510 and K624 at the intracellular end of the pore have greatly reduced transport activity—these residues are implicated in MD simulations (see also Supplementary Fig. 10a, b); mean ± SEM. f Homologous to hNKCC1 (a), the extracellular gate of mKCC2 is restricted by hydrogen bonds between R142 of TM1b and E224 of TM3. g Potential intracellular-gating residues of mKCC2: homologous to hNKCC1 (c), R193 of ICL1 in mKCC2 is close to D539 of TM8.