The daf-19 and nphp-2 mutants show defects in the localization of TAX-4. (A) TAX-4 is mislocalized in the daf-19 mutant. Instead of its wild-type localization at the ciliary base, TAX-4 in the daf-19 mutant is seen in the finger compartment, probably along the IFs. (B) TAX-4 localizes to the inversin compartment of the cilium. In amphid channel cilia, TAX-4 colocalizes with NPHP-2 in the proximal part of the cilium, above the transition zone (TZ, marked by MKSR-2) and the basal body (BB, marked by XBX-1). (C) TAX-4 is mislocalized in amphid cilia of the nphp-2 mutant. Wild-type cilia display discrete localization of TAX-4 at the proximal and not in the distal part of the cilia, whereas nphp-2 cilia show GFP signal leaking into the distal part of cilia. The histograms show the frequency distribution of the signal length at proximal and distal parts in cilia of wild-type (n = 44) and nphp-2 (n = 24) worms. Scale bars: 1 µm.