COQ10B is a START domain lipid-binding protein localized to the mitochondrial inner membrane that is essential for coenzyme Q (CoQ) function in cellular respiration 1. As a functional ortholog of yeast Coq10, COQ10B rescues respiratory defects and oxidative stress sensitivity in coq10 deletion mutants, demonstrating functional conservation across organisms 1. The protein likely functions as a chaperone facilitating CoQ delivery to respiratory complexes rather than participating directly in CoQ biosynthesis 1. COQ10B plays critical roles in mitochondrial respiration and antioxidant defense. Cadmium-induced renal cell apoptosis involves COQ10B reduction and impaired complex III and V function, linking CoQ10B deficiency to mitochondrial respiratory chain dysfunction and oxidative stress 2. Serum COQ10B levels are significantly decreased in Moyamoya disease patients, correlating with endothelial progenitor cell dysfunction and abnormal mitochondrial parameters 3. Clinically, COQ10B emerges as a potential diagnostic and therapeutic target in multiple conditions. COQ10B knockdown inhibits esophageal squamous cell carcinoma proliferation, migration, and invasion while promoting apoptosis 4. COQ10B was identified among nine signature genes predicting head and neck squamous cell carcinoma radiotherapy resistance 5. Additionally, reduced ferroptosis-related CoQ10B expression contributes to vascular endothelial injury in pregnancy-induced hypertension 6.