Component of the coenzyme Q biosynthetic pathway. May play a role in organizing a multi-subunit COQ enzyme complex required for coenzyme Q biosynthesis. Required for steady-state levels of other COQ polypeptides. Cofactor biosynthesis; ubiquinone biosynthesis. Component of a multi-subunit COQ enzyme complex, composed of at least coq3, coq4, coq5, coq6, coq7 and coq9. Belongs to the COQ4 family. Extended N-terminus. Extended N-terminus.