Category: biosynthesis
CoQ10 (ubiquinone-10) is the lipid-soluble mobile electron carrier of the ETC between Complex I/II and Complex III. Synthesized from tyrosine (provides the quinone head group via 4-hydroxybenzoate / 4-HB) + the mevalonate pathway (provides the polyprenyl tail — branches off from the cholesterol synthesis pathway, see cholesterol_synthesis). STATINS deplete CoQ10 because they block HMG-CoA reductase upstream of the polyprenyl-tail branch. The hypothesis that statin-related myalgia is CoQ10-depletion-mediated has been investigated and is inconclusive — supplementation trials for statin myalgia show mixed effect. Mitochondrial CoQ10 deficiency syndromes (genetic — COQ2, COQ4, COQ7, COQ8B mutations) cause nephrotic syndrome + encephalopathy + cardiomyopathy and DO respond to high-dose CoQ10 (200-1200 mg/d).