Movie 3

Repetitive [Ca²⁺]_fla elevations influence pausing of retrograde IFT.
TIRF imaging of IFT54-mScarlet in the flagellum shown in Video 2. In the initial period where no [Ca²⁺]_fla elevations were observed (Movie 2), IFT particles pause and accumulate in distal regions and very few retrograde IFT trains can be observed. After 40 s, when the series of repetitive [Ca²⁺]_fla elevations can be observed in Movie 2, the movement of IFT trains is noticeably different, with distinct retrograde IFT trains present.