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 (PubMed:23637185). Acts also as a positive regulator of hedgehog signaling and regulates ciliary function (PubMed:29290584). Forms a complex with the beta and gamma subunits of the GTP-binding protein, transducin. Interacts with the CCT chaperonin complex (By similarity). Conditional deletion in photoreceptor cells leads to 50-fold decrease in Gbeta-Ggamma dimer formation and more than 10-fold decrease in light sensitivity. A 20-fold reduction in Gbeta5 and RGS9-1 expression is also observed, causing a 15-fold delay in the shutoff of light responses. Belongs to the phosducin family.