Two rows of PKD2 line the cilium. (A) Schematic representation of an adhered Chlamydomonas cell (a), TIRF image (b), and kymogram (c) of a pkd2 PKD2-GFP (b) and a pkd2 PKD2–mNG (c) cell. Arrowheads indicate the exclusion zone. The trajectories of PKD2-FP undergoing IFT (red arrows) and diffusion (green arrowheads) are marked. Horizontal trajectories indicate stationary PKD2-mNG particles. Bars = 2 s and 2 µm. (B) TIRF (a and b) and SIM (c) images of live pkd2 PKD2-mNG cells; the inset in c shows the boxed area at higher magnification. Bars = 2 µm. (C) Kymograms showing stepwise bleaching (arrowheads) of stationary PKD2-mNG particles (a and b) and of a PKD2-mNG particle freshly delivered by IFT (arrow) indicative of the presence of multiple copies of tagged PKD2 in each particle. The ciliary base (B) and tip (T) are indicated. Bars = 2 s and 2 µm.