Bardet-Biedl syndrome 2 protein (BBS2)

The BBSome complex is supposed to function as a coat complex required for sorting of certain membrane proteins to the primary cilia. This ciliogenic function is mediated in part by the Rab8 GDP/GTP exchange factor, which localizes to the basal body and contacts that the BBSome.

Rab8(GTP) enters the primary cilium and promotes expansion of the ciliary membrane. Firstly the BBSome associates with the ciliary membrane and binds to RAB3IP/Rabin8, the guanosyl exchange factor (GEF) for Rab8 and subsequently the Rab8-GTP localizes to the cilium and promotes docking and fusion of carrier vesicles to the bottom of the ciliary membrane.