The IFT dynein travels on both sides of the axoneme in association with IFT proteins. (A) Temporal projection of the flagellum in a cell expressing GFP::DHC2.2. The region of interest (ROI) at the tip of the flagellum is indicated with left (green) and right (magenta) sides highlighted. (B) The kymographs are shown for the left and right side in the corresponding colors. Bars: 2.5 µm (horizontal bar); 5 s (vertical bar). (C) Kymograph analysis of a cell expressing mNG::IFT81 (left) and TdT::DHC2.1 (middle). On the merged panels, mNG::IFT81 is shown in green, and TdT::DHC2.1 is in magenta. Both proteins colocalized in moving but also in standing trains shown in the regions of interest. White arrowheads indicate arrested trains, while yellow arrowheads indicate an arrested train that started moving again. Even in these conditions, mNG::IFT81 and TdT::DHC2.1 remained associated. The white asterisk on the merged panel indicates a rare example of mNG::IFT81 material that was not associated with TdT::DHC2.1 and that remained immotile at the far distal end of the flagellum. However, the resolution was not sufficient to rule out the possibility that dynein could travel without cargo on other microtubules.