The small GTPases Rab are key regulators in vesicle trafficking (By similarity). Essential for maintaining the integrity of endosome-trans-Golgi network structure (By similarity). Together with LRRK2, plays a role in the retrograde trafficking pathway for recycling proteins, such as mannose 6 phosphate receptor (M6PR), between lysosomes and the Golgi apparatus in a retromer-dependent manner (By similarity). Recruits LRRK2 to the Golgi apparatus and stimulates LRRK2 kinase activity (By similarity). Regulates also neuronal process morphology in the intact central nervous system (CNS) (By similarity). Interacts with LRRK2. Colocalizes with GM130 at the Golgi apparatus (By similarity). Colocalizes with LRRK2 at dynamic tubules emerging from and retracting to the Golgi apparatus (By similarity). Colocalizes with TGN46 at the trans-Golgi network (TGN) (By similarity). Belongs to the small GTPase superfamily. Rab family.