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. 2020 Nov;107:82–90. doi: 10.1016/j.semcdb.2020.05.021

Fig. 1.

Fig. 1

Overview of the IFT cycle and anterograde IFT trains.

(A) Schematic of the IFT cycle. (B) Diagram of an anterograde IFT train moving to the tip the cilium. (+) and (-) indicate polarity of the microtubule (MT) doublet, which consists of a complete A-tubule attached to an incomplete B-tubule. Dynein-2 complexes along the train are shown in alternating dark and light blue for distinction. Length of the depicted train is 180 nm (anterograde trains vary in length from 100 to 700 nm in C. reinhardtii [28]). (C) Cross-section view depicting an anterograde IFT train moving in the confined space between the microtubule doublet, outer dynein arms (ODAs), and ciliary membrane. Created using EMD-4304 (sub-tomogram average of IFT-A), EMD-4303 (sub-tomogram average of IFT-B and dynein-2) [28], PDB-6SC2 (atomic model for dynein-2) [49], EMD-6872 (sub-tomogram average of microtubule-doublets and ODAs) [50], and PDB-4RH7 (used to model ODA stalks) [51]. Approximate position of kinesin is shown with orange triangles. (D) Sub-tomogram averages of IFT-A (yellow) at 33 Å resolution (EMD-4304) and IFT-B (grey) and dynein-2 (blue) at 37 Å resolution (EMD-4303) [28].