Fig. 1.

CoQ₁₀ biosynthetic pathway with eight known biosynthetic enzymes denoted as COQ1-8. CoQ₁₀ is composed of a benzoquinone and a decaprenyl side chain. While the quinone ring is derived from amino acids tyrosine or phenylalanine, the isoprenoid side chain is produced by addition of isopentenyl pyrophosphate molecules to geranylgeranyl pyrophosphate (derived from mevalonate pathway) by decaprenyl diphosphate synthase. After para-hydroxybenzoate and decaprenyl pyrophosphate are produced, at least seven enzymes (encoded by COQ2-8) catalyze condensation, methylation, decarboxylation, and hydroxylation reactions to synthesize CoQ₁₀