Enables GTP binding activity. Involved in endocytosis and vesicle transport along microtubule. Acts upstream of or within endoplasmic reticulum to Golgi vesicle-mediated transport. Located in several cellular components, including Golgi membrane; early endosome; and neuronal cell body. Is active in presynapse. Orthologous to human RAB1A (RAB1A, member RAS oncogene family). [provided by Alliance of Genome Resources, Apr 2022]