Figure 1.

Electron cryo-tomography structures of cilium inner Junctions. (A) A schematic diagram of a cilium in Tetrahymena, including BB and axoneme. The three regions in the BB, the proximal, central core, and distal, are highlighted in different green colors. Their approximate longitudinal spans are indicated. The three grey-colored cross-sections indicate the location of the structures presented in this work. (B) Left, schematic diagrams of the cross-section of the proximal, the central core region of the BB, and the axoneme. Right, representation of the triplet MT or doublet MT from the three regions. Distinct structures attached to the microtubule wall in each region, such as the cartwheel and A-C linker in the proximal region, the inner scaffold in the central core region, and the Dynein complexes (outer Dynein arm, ODA; inner Dynein arm, IDA; Dynein regulatory complex, DRC) and radial spokes (RS) in the axoneme, are indicated. The red dashed-line boxes highlight the A-B inner Junctions (IJ). (C) Three representative subtomograms-averaged structures presented in this work. From bottom to top are the proximal, the central core region of the BB, and the axoneme, as indicated in the cartoons in (B).