Rab5 is a small GTPase that is a key regulator of early endosome function. It is involved in the recruitment of effector proteins that mediate endosome fusion, motility, and cargo sorting. Rab5 also participates in the formation of early endosomes from the plasma membrane and ensures the maturation of these organelles. Its activity is tightly regulated by GDP-GTP exchange factors (GEFs) and GTPase-activating proteins (GAPs).
