COQ2 encodes para-hydroxybenzoate:polyprenyltransferase, an enzyme of the ubiquinone (Coenzyme Q) biosynthetic pathway (1). Ubiquinone serves to transport electrons between the respiratory enzyme complexes of the mitochondrial inner membrane. Coq2p catalyzes the prenylation of para-hydroxybenzoate to form 3-hexaprenyl-4-hydroxybenzoate, which is the second committed step in the pathway. coq2 mutants display a ubiquinone biosynthetic defect, lack para-hydroxybenzoate:polyprenyltransferase activity, and also exhibit a respiratory growth defect (inability to grow on nonfermentable carbon sources) (1).

Coq2p is located in the mitochondrion (2, 1, 3) and is likely to be a constituent of the inner membrane, as is its rat ortholog (4). Genetic interactions suggest that the ubiquinone biosynthetic enzymes Coq1p, Coq2p, Coq3p, Coq4p, Coq5p, Coq6p, Cat5p, and Coq8p may form a complex in the mitochondrion (5, 6). A substantial amount of Coq2p activity also copurifies with the microsomal fraction, but the significance of this is unclear (1).

COQ2 is well-conserved, with cross-complementing orthologs found in species from bacteria (7) to mammals (8) and plants (9). Mutations in the human ortholog COQ2 (OMIM) cause primary Coenzyme Q10 deficiency (10).

Last updated: 2006-09-13