Ciliary targeting

In addition to the Golgi, another fundamental question attracting us is the mechanism behind the ciliary targeting. The ciliary membrane is an extension of the plasma membrane, but it has a unique enrichment of proteins for its sensory functions. Despite more than a decade of intensive study, how ciliary residents target to the cilium remains an open question. By quantitative measurement of the ciliary localization, we discovered that transportin1, Rab8, and the ciliary targeting sequence could assemble a ternary complex to target diverse ciliary residents (Madugula et al., J. Cell Sci., 2016). Furthermore, we noticed the similarity between the ciliary targeting and the nucleocytoplasmic trafficking and proposed the Rab-importin-based ciliary retention mechanism (Lu and Madugula, Cell. Mol. Life Sci., 2017). Our model can explain most experimental data, especially the paradoxical observation that ciliary membrane residents accumulate in the cilium yet possess very high mobility along the entire ciliary membrane.