ARL6 and Bardet-Biedl syndrome: The conventional retrieval pathway for activated GPCRs from the primary cilium back into the cytoplasm relies on the β-arrestin 2 and the BBSome, a complex of Bardet-Biedl Syndrome (BBS) proteins that forms a membranous coat in association with the Arf-like GTPase Arl6 [329–331].