Fig. 6.

Crystal structure of the apo LjCASTOR gating ring. a Surface-rendered representation of the apo gating ring, which is no longer fourfold symmetrical. Distances are measured between the Cα atoms of Thr 323 s from two neighboring or diagonal subunits. b Surface-rendered representation of the Ca²⁺-bound gating ring. c Single subunit superimposition between Ca²⁺-bound (RCK1 in pink and RCK2 in magenta) and apo (RCK1 in light blue and RCK2 in blue) structures. The RCK1 N-lobes were used in the structural alignment. Insets are zoomed-in view of the structural differences at the cluster I (left) and II sites (right). In each inset, the other subdomains of no interest were removed for visual clarity