Cilia are microtubule based organelles and perform motile, sensing and signaling functions. The assembly and maintenance of cilia depend on intraflagellar transport. Besides ciliary localization, most IFT proteins accumulate at basal bodies. However, little is known about the molecular mechanism of basal body targeting of IFT proteins. We first identified the possible basal body targeting sequence of IFT46 by expressing IFT46 truncations in ift46-1 mutant. The C-terminal sequence 246-321 aa, termed BBTS3, was sufficient to target YFPs to basal bodies in ift46-1. Interestingly, BBTS3 is also responsible for the ciliary targeting of IFT46. BBTS3::YFP moves bidirectionally in flagella and interacts with other IFT-B proteins. Using IFT and motor mutants, we show that the basal body localization of IFT46 depends on IFT52, but not on IFT81, IFT88, IFT122, FLA10 or DHC1b. IFT52 interacts with IFT46 through L285/L286 of IFT46 and recruits it to basal bodies. Ectopic expression of IFT52C in the nucleus resulted in accumulation of IFT46 in nuclei. These data suggest IFT52 and IFT46 can preassemble as a complex in the cytoplasm, which is then targeted to basal bodies.
- Received December 22, 2016.
- Accepted March 14, 2017.
- © 2017. Published by The Company of Biologists Ltd