http://en.wikipedia.org/wiki/NADH_de...8ubiquinone%29

Complex I (EC 1.6.5.3) (also referred to as NADH:ubiquinone oxidoreductase or, especially in the context of the human protein, NADH dehydrogenase (ubiquinone)) is an enzyme of the respiratory chains of myriad organisms from bacteria to humans. It catalyzes the transfer of electrons from NADH to coenzyme Q10 (CoQ10) and, in eukaryotes, it is located in the inner mitochondrial membrane. It is one of the "entry enzymes" of oxidative phosphorylation in the mitochondria.