Fig. 4. IFT88/polaris is targeted to the centrosome by its TRP domains. (A) Deletion constructs. Numbers indicate the positions of amino acids, black boxes designate the predicted coiled-coil domain of IFT88/polaris, grey boxes designate the tetratricopeptide repeat domains (TPR). Results of the immunolocalization of GFP-tagged polypeptides are summarized on the right. (B) HeLa cells were transiently transfected with GFP-IFT88/polaris full-length and, 24 hours later, processed for immunofluorescence microscopy (GFP staining). Depending on the expression level, ectopic IFT88/polaris expression resulted in the formation of a single dot (left panel) or multiple dots (right panel). The arrowhead points to the dot containing the centrosome (-tubulin labeling, data not shown). Bars, 10 µm. (C) Phenotypes observed after ectopic expression of GFP-tagged truncated IFT88/polaris polypeptides (green). Transfected cells were stained with -tubulin (red) 24 hours post transfection. Although polypeptides 1, 4 and 5 produced proteins that were not found at the centrosome (see 4 and 5), other polypeptides containing TRP domains (2, 3, 6 and 7) produced proteins that were recruited to the centrosome (see 6). Depending on expression levels, ectopic expression of mutants 2, 3, 6 and 7 resulted in the formation of a single dot (6 first panel) or of multiple dots (6, second panel). Bars, 10 µm.