Cilium-specific protein required for the regulation of cilium/flagellum formation (PubMed:19254375). Involved in centriole duplication (By similarity). May play a role in melanosome trafficking (PubMed:24550735). Expressed in cilia cells in the spinal canal, pronephros and Kupffer's vesicle. Morpholino knockdown of the protein leads to truncated cilia formation and impaired intraflagellar transport processes. Belongs to the CEP131 family.