Fig. 3. Colocalization of the NPH-1 and NPH-4 proteins to the transition zone at the base of cilia in C. elegans. (A) Transgenic lines were generated that express NPH-1::CFP and NPH-4::YFP under control of their endogenous promoters. NPH-1 and NPH-4 colocalized to the distal end of the dendrites of the ciliated sensory amphid and labial neurons in the head of the worm (left panels) and the sensory rays of the male tail (right panels). (B,C) The localization of NPH-1 (B)and NPH-4 (C)was further evaluated by generating transgenic lines that co-express the IFT protein, CHE-13. CHE-13 was detected at the transition zones (arrowheads) and in the cilium axoneme (arrows); however, both NPH-1 and NPH-4 were restricted to the transition zone. There was no detectable signal for NPH-1 or NPH-4 in the axoneme. For enlarged images of the cilium region see Fig. S1 in supplementary material.