Required for ciliation. Recruits the RABL2B GTPase to the ciliary base to initiate ciliation. After specifically capturing the activated GTP-bound RABL2B, the CEP19-RABL2B complex binds intraflagellar transport (IFT) complex B from the large pool pre-docked at the base of the cilium and thus triggers its entry into the cilia. Involved in the early steps in cilia formation by recruiting the ciliary vesicles (CVs) to the distal end of the mother centriole where they fuse to initiate cilium assembly. Involved in microtubule (MT) anchoring at centrosomes. Interacts with CEP43; this interaction is required for its localization to the mother centriole. Interacts (via residues 121-150) with RABL2B. Interacts (via C-terminus) with CEP350; this interaction is required for its localization to the mother centriole. Associates with the mother centriole in early interphase. Localizes to spindle poles during mitosis, and to distinct foci oriented towards the midbody at telophase. Localizes slightly apical to the subdistal appendage on the mother centriole, but below the distal appendage. Belongs to the CEP19 family.