Figure 3. Inter-domain interfaces.

a, Superposition of a single subunit aligned by the RCK2 domains. S6 and RCK1 N-lobe are colored blue in the Ca²⁺-bound state and red in the EDTA state. b, Superposition of Ca²⁺-bound (blue) and EDTA (red) states aligned by their RCK2 domains with front and rear subunits of the TMD and gating ring removed. c, Superposition of the TMD of a single subunit aligned by the pore helix and selectivity filter. S4 and S5 are colored blue in the Ca²⁺-bound state and red in the EDTA state. Interacting residues on S4 and S5 are shown as sticks.