Component of the centrioles that acts as a positive regulator of centriole elongation (PubMed:24997988). Promotes assembly of centriolar distal appendage, a structure at the distal end of the mother centriole that acts as an anchor of the cilium, and is required for recruitment of centriolar distal appendages proteins CEP83, SCLT1, CEP89, FBF1 and CEP164. Not required for centriolar satellite integrity or RAB8 activation. Required for primary cilium formation (PubMed:23769972). Required for sonic hedgehog/SHH signaling and for proteolytic processing of GLI3. {ECO:0000269|PubMed:23769972, ECO:0000269|PubMed:24997988}. This is the function of C2CD3 (C2 domain containing 3 centriole elongation regulator, ENSG00000168014).