Required for the maintenance and formation of cilia and participates in the control of flagellar assembly/disassembly at the tip. Involved in regulating the transition between anterograde and retrograde intraflagellar transport at the tip. Component of the IFT complex B, the core composed of IFT25, IFT27, IFT46, IFT52, IFT74, IFT81 and IFT88 as well as associated subunits IFT20, IFT57, IFT80 and IFT172. Interacts with microtubule end-binding protein 1 (MAPRE1/EB1). Belongs to the IFT172 family.