Required for normal functioning of the late endocytic pathway including lysosome motility and late endosome-lysosome fusion (PubMed:16537643, PubMed:29940804, PubMed:30115618). Not required for the delivery of lysosomal membrane protein-containing vesicles to late endosomes (PubMed:29940804). In larval motorneurons, mediates the anterograde axonal long-range transport of presynaptic lysosome-related vesicles required for presynaptic biogenesis and synaptic function (PubMed:30174114, PubMed:30115618). Essential role in chromosome segregation (PubMed:15331635). Interacts with tubulin (PubMed:15331635). Interacts (in GTP-bound form) with Rilpl (PubMed:30115618). Interacts with unc-104 (PubMed:30174114). Localizes the perinuclear region when associated with CG11448. Expressed throughout development, from embryo to adult stage, in different tissues such as larval motor neurons, salivary glands, testis and ovaries (at protein level). Lethal from late larval stages (PubMed:29940804, PubMed:30115618). In garland cells, results in defective late endosome-lysosome fusion and inability to form a rapidly exchanging terminal lysosomal network (PubMed:29940804). In motor neurons, results in defective anterograde axonal long-range transport of lysosome-related vesicles which leads to defective protein localization to presynaptic active zone and synaptic vesicles (PubMed:30174114, PubMed:30115618). This results into a reduction of number of boutons per synapses which limits neurotrasmitter release and leads to posterior paralysis (PubMed:30174114, PubMed:30115618). RNAi-mediated knockdown in larval presynaptic motoneurons results in defective presynaptic biogenesis (PubMed:30174114). Belongs to the small GTPase superfamily. Arf family.