May be involved in autophagy-related processes. Unlike other Rab family members, does not interact with GDP dissociation inhibitors (GDIs), including ARHGDIA and ARHGDIB. Only about 20% is recovered in the particulate fraction. Widely expressed, with highest expression in brain. Isoprenylation is inefficient compared to other Rab family members. The unusual Ser-67, instead of a conserved Gln in other family members, is the cause of low GTPase activity. As a result, the predominant nucleotide associated with the protein is GTP. Belongs to the small GTPase superfamily. Rab family.