Cilium-specific protein required to control the microtubule-based, ciliary axoneme structure. May act by maintaining the association between IFT subcomplexes A and B. Binds GTP but is not able to hydrolyze it; the GTPase activity remains unclear. Required to pattern the neural tube. Involved in cerebral cortex development: required for the initial formation of a polarized radial glial scaffold, the first step in the construction of the cerebral cortex, by regulating ciliary signaling. Regulates the migration and placement of postmitotic interneurons in the developing cerebral cortex Required during embryogenesis for cilia formation in multiple organs such as the pronephric duct. Interacts with EXOC2; regulates ARL13B localization to the cilium membrane. Associates to the cilium membrane via palmitoylation. Localizes to proximal ciliary membranes, to an inversin-like subciliary membrane compartment, excluding the transition zone. Cilium-specific. Detected at the 4- to 32-cell stage, suggesting it is expressed maternally. Embryos have a ventrally curved tail, ciliary defects and cystic kidneys. Belongs to the small GTPase superfamily. Arf family. Contaminating sequence. Potential poly-A sequence.