Functions as a co-chaperone for CCT in the assembly of heterotrimeric G protein complexes, facilitates the assembly of both Gbeta-Ggamma and RGS-Gbeta5 heterodimers. Acts also as a positive regulator of hedgehog signaling and regulates ciliary function. Interacts with the CCT chaperonin complex (By similarity). Forms a complex with the beta and gamma subunits of the GTP-binding protein, transducin. Additional isoforms seem to exist. Belongs to the phosducin family.