Extended Data Fig. 6: Overview of all the structures obtained from the MthK Ca²⁺ dataset.

a, The structures with clear transmembrane density were kept; they were classified into four groups according to the tilt angle between the nanodisc (TMD) and RCK ring: highly tilted (red), medium tilted (blue), mildly tilted (green) and closed state (yellow). Finally, there are nine structures in total: three different structures in the highly tilted group (MthK Ca²⁺ states 1, 1.2 and 1.3), two different structures in the medium tilted group (MthK Ca²⁺ state 2 and 2.2), three different structures in the mildly tilted group (MthK Ca²⁺ state 3, 3.2 and 3.3), and one closed state. b, Cryo-EM data processing workflow for only the gating ring structures of the MthK Ca²⁺ dataset, excluding the closed state. Two different structures were identified by Relion 3D classification (named RCK state 1 and RCK state 2). c, Overlay of RCK states 1 and 2. Slight differences are observed between the two structures.