Extended Data Fig. 4: Structural features of the cytosolic regions.

a, The cytosolic region consists of two separate but interacting parts. Cytosolic map 1 is in close contact with the S6 segments of CATSPER2 and CATSPER3. A density surrounded in the bottom of cytosolic map 1 (shown in green) is connected to the density of the S6 segment of CATSPER3 and may belong to the carboxyl end of CATSPER3. Owing to limited resolution, the identity of cytosolic map 1 remains to be determined. Cytosolic map 2, however, is likely to be the subcomplex of EFCAB9 and CATSPERζ. The maps were generated in ChimeraX. b, Predicted structures of EFCAB9 by tFold and CATSPERζ by trRosseta. EFCAB9 has two EF-hand motif-containing lobes, which is very similar to calmodulin. CATSPERζ consists mainly of α-helices. c, Docking of the predicted structures of EFCAB9 and CATSPERζ into cytosolic map 2. The two lobes of EFCAB9 are in a compact conformation instead of the extended conformation in the predicted structure. The main body of CATSPERζ (light cyan in b) can be fitted into the remaining density near EFCAB9 in cytosolic map 2. Several fitted α-helices are indicated by arrows.