Required for ciliogenesis. Also plays a role in mitochondrial metabolism where it may modulate complex IV activity. Localizes to the distal appendage region of the centriole, which anchors the mother centriole to the plasma membrane. Homozygous deletion comprising CEP89 and SLC7A9 genes has been reported in a patient with isolated complex IV deficiency, intellectual disability and multisystemic problems that include cystinuria, cataract, broad based walking pattern and deafness.