Figure 10. Glide symmetry model of NKCC1 as proposed byLytle et al. (1998).

Under isotonic conditions, empty NKCC1 binds in the order: one Na⁺, one Cl⁻, one K⁺ and a second Cl⁻. After translocation, NKCC1 releases in the same order: the Na⁺, the first Cl⁻, the K⁺ and the second Cl⁻.Then, the cotransporter translocates empty and the cycle repeats. Under hypertonicity, partial reactions occur with the transporter reversing inside prior to unloading the second Cl⁻ and outside prior to unloading the Na⁺. As a result, these partial cycles exchange external K⁺ and Cl⁻ for internal K⁺ and Cl⁻, i.e. K⁺/K⁺ and Cl⁻/Cl⁻ exchanges. Externally loaded ions are represented in black, internally loaded ions are represented in red.