Fig. 5: Ion-binding probability densities of mKCC2.

a K⁺ and Cl⁻ (Cl⁻-1) binding sites of mKCC2 based on molecular dynamic simulations. Similar to hNKCC1, K⁺ is stabilized by the interaction with Y218 in TM3, N133 and I134 in TM1a, T435 and P432 in TM6, and the Cl⁻ ion. The Cl⁻ binding site is stabilized by interaction with G136, V137, and I138 in TM1 and by the K⁺ ion. b A second Cl⁻ binding site (Cl⁻-2) of mKCC2. Similar to (Cl⁻-2) in hNKCC1, this Cl⁻ is stabilized by the interaction with G436, I437, and M438 in TM6, and Y592 in TM10. c Four Cl⁻ ion probability densities in mKCC2 based on molecular dynamic simulations. d Time evolution of the distance of the three ions (K⁺, Cl⁻-1, and Cl⁻-2) from its proposed binding sites based on molecular dynamics simulation. The Cl⁻ ion escapes from the Cl⁻-1 site to the neighboring Cl⁻-3 site after 300 ns.