Figure 1. .
CoQ10 biosynthetic pathway. Isopentenyl diphosphates derived from the mevalonate pathway generate geranylgeranyl diphosphate. Additional isopentenyl diphosphates are added by decaprenyl diphosphate synthase, which, in humans is a heterotetramer composed of two prenyl diphosphate synthase subunit 1 and two prenyl diphosphate synthase subunit 2 molecules. PHB is derived from the amino acids tyrosine or phenylalanine. After PHB and decaprenyl diphosphate are produced, at least seven enzymes catalyze condensation, methylation, decarboxylation, and hydroxylation reactions to synthesize CoQ10.1,2