The proposed CoQ biosynthesis pathway in <i>S. cerevisiae</i>, <i>S. pombe</i>, humans, and <i>A. thaliana</i>.

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