The small GTPases Rab are key regulators of intracellular membrane trafficking, from the formation of transport vesicles to their fusion with membranes. Rabs cycle between an inactive GDP-bound form and an active GTP-bound form that is able to recruit to membranes different set of downstream effectors directly responsible for vesicle formation, movement, tethering and fusion. That Rab may play a role in protein transport from recycling endosomes to lysosomes regulating, for instance, the degradation of the transferrin receptor. Involved in autophagy (By similarity). Rab activation is generally mediated by a guanine exchange factor (GEF), while inactivation through hydrolysis of bound GTP is catalyzed by a GTPase activating protein (GAP) (By similarity). That Rab is activated by DENND3, a guanine exchange factor. Interacts with RABIF (PubMed:21194374). Interacts with OPTN (By similarity). Interacts with LRRK2; interaction facilitates phosphorylation of Ser-106 (PubMed:26824392). Interacts with GDI1, GDI2, CHM and CHML; these interactions are disrupted by phosphorylation on Ser-106 (PubMed:26824392, PubMed:29125462). Interacts with RILPL1 and RILPL2; these interactions are dependent on phosphorylation of Ser-106 (PubMed:26824392, PubMed:29125462). Phosphorylation of Ser-106 in the switch II region by LRRK2 prevents the association of RAB regulatory proteins, including CHM, CHML and RAB GDP dissociation inhibitors GDI1 and GDI2. Belongs to the small GTPase superfamily. Rab family. Intron retention. Intron retention.