The Rab family of proteins is a member of the Ras superfamily of small G proteins.[1] Approximately 70 types of Rabs have now been identified in humans.[2] Rab proteins generally possess a GTPase fold, which consists of a six-stranded beta sheet which is flanked by five alpha helices.[3] Rab GTPases regulate many steps of membrane trafficking, including vesicle formation, vesicle movement along actin and tubulin networks, and membrane fusion. These processes make up the route through which cell surface proteins are trafficked from the Golgi to the plasma membrane and are recycled. Surface protein recycling returns proteins to the surface whose function involves carrying another protein or substance inside the cell, such as the transferrin receptor, or serves as a means of regulating the number of a certain type of protein molecules on the surface.