Fig. 4.
Three-dimensional localization of the DRC8/11 subcomplex at the proximal lobe of the N-DRC linker using cryo-ET. (A–F) Tomographic slices of the averaged 96-nm repeats of Chlamydomonas WT (A–C) and drc11 axonemes (D–F) viewed in cross-sectional (A and D) and longitudinal (B, C, E, and F) orientations. The white lines indicate the locations of the slices in the respective panels. Cryo-ET densities corresponding to DRC8/11 in the nexin–dynein regulatory complex (N-DRC) of WT (orange arrowheads in A–C) were missing from the drc11 axonemes (white arrowheads in D–F). (G–L) Isosurface renderings show the 3D structures of the averaged axonemal repeats of WT (G–I) and drc11 (J–L) in cross-sectional (G and J), longitudinal (H and K), and enlarged longitudinal bottom views (I and L; looking from the axoneme center outward). The structural difference between the WT and drc11 is manually colored orange in G–I and includes a major portion of the proximal lobe (pL). Other labels: a–e and g, inner dynein arm isoforms; At, A-tubule; Bt, B-tubule; dL, distal lobe; I1α/I1β/ICLC, α- and β-heavy chain, and intermediate/light-chain complex of I1 dynein; IDA, inner dynein arm; ODA, outer dynein arm; RS, radial spoke. (Scale bar: 10 nm [in E, valid also for A, B, and D], 10 nm [in F, valid also for C].)