The function of Ensembl gene identifier ENSG00000167186 (COQ7, coenzyme Q7, hydroxylase) is as follows. Catalyzes the hydroxylation of the 5-methoxy-2-methyl-3-(all- trans-polyprenyl)benzoquinone at the C6 position and participates in the biosynthesis of ubiquinone (Probable). Catalyzes the reaction through a substrate-mediated reduction pathway, whereby NADH shuttles electrons to 5-methoxy-2-methyl-3-(all-trans-decaprenyl)benzoquinone, which then transfers the electrons to the two Fe(3+) centers (PubMed:23445365). The binding of 5-methoxy-2-methyl-3-(all-trans- polyprenyl)benzoquinone (DMQn) mediates reduction of the diiron center by nicotinamide adenine dinucleotide (NADH) and initiates oxygen activation for subsequent DMQ hydroxylation (PubMed:23445365). The physiological substrates are 5-methoxy-2-methyl-3-(all-trans- nonaprenyl)benzoquinone (DMQ(9)) and 5-methoxy-2-methyl-3-(all-trans- decaprenyl)benzoquinone (DMQ(10)), however in vitro the enzyme does not have any specificity concerning the length of the polyprenyl tail, and accepts tails of various lengths with similar efficiency (PubMed:23445365, PubMed:28409910). Also has a structural role in the COQ enzyme complex, stabilizing other COQ polypeptides. Involved in lifespan determination in a ubiquinone-independent manner (By similarity). Plays a role in modulating mitochondrial stress responses, acting in the nucleus, perhaps via regulating gene expression, independent of its characterized mitochondrial function in ubiquinone biosynthesis (PubMed:25961505). {ECO:0000255|HAMAP-Rule:MF_03194, ECO:0000269|PubMed:23445365, ECO:0000269|PubMed:25961505, ECO:0000269|PubMed:28409910, ECO:0000305|PubMed:23445365, ECO:0000305|PubMed:28409910, ECO:0000305|PubMed:38425362}.