Rab5 is a member of the Ras superfamily of small Rab GTPases. Rab5 is localized at the plasma membrane and early endosomes and functions as a key regulator of vesicular trafficking during early endocytosis (1). The conformational change between Rab5 GTP/GDP states is essential for its biological function as a rate limiting regulator at multiple steps during endocytosis (1,2). Rab5 exerts its function by interacting with several Rab5-specific effectors (1-3). These proteins form complexes with Rab5 on a specialized Rab domain of the endosome and promote recycling of Rab5-cargo targets between endosome and the plasma membrane.
