RAB cascade dynamics of RAB8 and RAB11 in cilia and membrane tubules

Rabs, a family of more than 60 small GTPases, play essential roles in membrane trafficking by switching from inactive GDP-bound to active GTP-bound states. RABs are believed to regulate membrane trafficking via cascades whereby an upstream active RAB recruits a GEF to activate a GDP-bound RAB functioning in the next step of membrane transport. Apart from the classic RAB5-RAB7 cascade important in endosome to lysosome maturation, little is known about this membrane trafficking mechanism. Here we investigate the RAB11-RAB8 cascade important in primary cilium assembly and neurite outgrowth, and the associated RAB8 GEF Rabin8.