Fibrocystin, polycystin-2, and smoothened take different trafficking routes to the primary cilium. (A) Summary of the trafficking rates of membrane protein delivery from the Golgi apparatus to the cilium. Membrane proteins are listed horizontally. shRNAs and MyoVb C-terminal tail expression are listed on the left side. (B) IFT20 localizes at the cis Golgi compartment where it interacts with the vesicle tethering golgin GMAP210. IFT20 also localizes to the medial Golgi compartment, the cilium, and the basal body. Subunits of the exocyst localize to the basal body. Exocyst subunits Exo70 and Sec8 interact with IFT20. BLOC-1 also interacts with the exocyst. The exocyst tethers vesicles containing ciliary membrane protein cargo to the base of the cilium before SNARE-mediated fusion. We propose that fibrocystin is using the direct trafficking pathway because it is affected only by knockdown of the IFT20-GMAP210 complex and the exocyst. Smoothened is likely using the lateral trafficking pathway because its delivery to cilia is not greatly affected by the knockdown of the IFT20-GMAP210 complex, and it is not affected by the knockdown of the exocyst or BLOC-1. The BLOC-1 subunit pallidin localizes to the basal body and its localization is partially dependent on IFT20. Pallidin interacts with IFT20 and polycystin-2. Knockdown of the BLOC-1 subunits pallidin and dysbindin affects the trafficking of polycystin-2 but not fibrocystin or smoothened. MyoVb C-terminal tail overexpression reduced ciliary polycystin-2 levels and caused its accumulation at the recycling endosome. Additionally, expression of dominant-negative Rab11aS25N perturbs polycystin-2 ciliary trafficking. This suggests that polycystin-2 is trafficked to the cilium through the recycling endosome. IFT20, BLOC-1, and the exocyst are acting together to deliver polycystin-2 cargo from the recycling endosome to the primary cilium.