The proposed CoQ biosynthesis pathway in S. cerevisiae, S. pombe, humans, and A. thaliana.

At least ten genes, three of which have unassigned roles, are responsible for CoQ biosynthesis in S. pombe. All of these S. pombe enzymes have human counterparts, but A. thaliana lacks Coq7 and a component of the prenyl diphosphate synthase in this plant species differs from that in S. pombe and humans. The functions of Coq4 and Coq9 are currently unknown. Coq8 is a protein kinase that regulates the stability of Coq proteins in S. cerevisiae. The involvement of pABA in the CoQ pathway in S. pombe, human and A. thaliana has not yet been established. For simplicity, ARH1 and YAH1, which are involved in CoQ synthesis through the regulation of Coq6 in S. cerevisiae, are not shown.