Extended Data Figure 9: Data collection, refinement statistics and structure validation.

a, Cryo-EM data collection and refinement statistics of the B complex structure. Different regions of the composite B complex structure were refined into B1, B4, B5, B6 and B7 maps as described (see Methods). b, FSC between local cryo-EM map regions and corresponding regions of the refined coordinate models. Note that the FSC curve for the B-specific proteins correlates with the local resolution in this sub-region of the B7 density (4.0–5.0 Å; Extended Data Fig. 3e), below the nominal resolution (4.0 Å).