Coenzyme Q also known as "Cytochrome c - Oxidoreducatase" is a protein involved in the oxidative phosphorylation and the production of ATP as the third protein along in the electron transport chain where it plays a vital role in the production of ATP by oxidative phosphorylation.
Coenzyme Q (sometimes called complex III) is a multisubunit transmembrane protein coded for both by mitochondrial and nuclear genomes - though the enzyme its present is present in mitochondria1.
1. Coenzyme Q – cytochrome c reductase - an overview | ScienceDirect Topics [Internet]. Sciencedirect.com. 2017 [cited 24 October 2017]. Available from: http://www.sciencedirect.com/topics/nursing-and-health-professions/coenzyme-q-cytochrome-c-reductase