CEP89 (centrosomal protein 89) is a dual-function protein essential for both ciliogenesis and mitochondrial metabolism. As a distal appendage component, CEP89 plays a specialized role in primary cilium dynamics, specifically regulating ciliary disassembly rather than assembly 1. CEP89 functions in preciliary vesicle recruitment by interacting with myristoylated Neuronal Calcium Sensor-1 (NCS1), which directly captures preciliary vesicles at the distal appendage 2. The protein is recruited to distal appendages through CEP83 in a hierarchical assembly pathway and is phosphorylated by TTBK2 kinase 34. In mitochondrial metabolism, CEP89 localizes to the intermembrane space and is required for complex IV activity and proper assembly 5. Loss of CEP89 function causes isolated complex IV deficiency, intellectual disability, and neurological dysfunction in humans, while Drosophila knockdown results in mitochondrial dysfunction, altered synaptic transmission, and learning defects 5. Clinically, CEP89 overexpression and copy number gains are associated with poor prognosis in ovarian cancer, suggesting potential therapeutic relevance 6. The protein also modulates G0 cell cycle arrest capacity, linking it to therapy resistance mechanisms 7.