Small GTPase-like component of the intraflagellar transport (IFT) complex B. Forms a subcomplex within the IFT complex B with IFT25. Has very low GTPase activity either because it lacks the conserved catalytic Gln in position 79 or because it requires some GTPase-activating protein (GAP) for GTP turnover. Component of the IFT complex B, the core composed of IFT25, IFT27, IFT46, IFT52, IFT74, IFT81 and IFT88 as well as associated subunits IFT20, IFT57, IFT80 and IFT172. Interacts with IFT25; the interaction is direct. Colocalizes with IFT25 at the distal-most portion of basal bodies, probably the transition zones, and concentrates in the basal body region. Belongs to the small GTPase superfamily. Rab family. Although similar to the small GTPase superfamily, lacks the conserved catalytic Gln in position 79 which is replaced by a Ser residue, possibly explaining the weak GTPase activity. In contrast to other members of the family, it is not prenylated (PubMed:21505417).