Plays a role in endocytosis and intracellular protein transport. Mediates trafficking of TF from early endosomes to recycling endosomes (PubMed:16537905). Required for NGF-mediated endocytosis of NTRK1, and subsequent neurite outgrowth (PubMed:21849477). Binds GTP and GDP and has low GTPase activity. Alternates between a GTP-bound active form and a GDP-bound inactive form (PubMed:16537905). Interacts directly with ZFYVE20 (By similarity). Binds EEA1 (By similarity). Interacts (in its GTP-bound form) with RABGEF1 (PubMed:21849477). Interacts (in its GTP-bound form) with RINL (PubMed:21419809). Recruited to phagosomes containing S.aureus or M.tuberculosis. Belongs to the small GTPase superfamily. Rab family.