Joubert syndrome Arl13b functions at ciliary membranes and stabilizes protein transport in Caenorhabditis elegans

Ciliary transmembrane protein localization is disrupted in arl-13(tm2322) mutants. (A and B) Representative fluorescence images of the distal head region (nose) of worms expressing gfp-tagged ODR-10, OSM-9, TAX-2, and PKD-2 are shown. In tm2322 mutants, abnormal accumulations (arrowheads) are found in ciliary axonemes (ODR-10), near the ciliary base (ODR-10 and TAX-2; asterisks), or within the distal dendrite (OSM-9; arrowhead). In tm2322 mutants, PKD-2::GFP ciliary abundance is elevated in CEM and RnB cells, with cell body levels reduced (shown for CEMs). c, cilium. (C) Analysis of PKD-2::GFP ciliary abundance in CEM cells. The ratio of PKD-2::GFP signal intensities in individual CEM cilia (F_cilia) and individual CEM cell bodies (F_{cell body}) is shown. All images were captured and analyzed using identical settings. The number of cilia analyzed is shown in parentheses. Error bars indicate SEM. Bars: (A and B [first and second columns]) 2 μm; (B, third and fourth columns) 10 μm.