Required for the maintenance and formation of cilia. Plays an indirect role in hedgehog (Hh) signaling, cilia being required for all activity of the hedgehog pathway. Interacts with IFT88 (PubMed:11062270). Interacts with IFT57 (PubMed:23810713). Interacts with RABL2/RABL2A; binds preferentially to GDP-bound RABL2 (PubMed:23055941). Co-localizes with RABL2/RABL2A in the midpiece of elongated spermatids within the testis (at protein level). Expressed in the flagellum of elongated spermatids and sperm in the testis lumen (at protein level) (PubMed:24339785). Belongs to the IFT172 family. Intron retention. The sequence is a pre-RNA and intronic sequences remain.