Editing Oxidative phosphorylation (section)

=== Electron transfer flavoprotein-Q oxidoreductase ===
[[Electron-transferring-flavoprotein dehydrogenase|Electron transfer flavoprotein-ubiquinone oxidoreductase]] (ETF-Q oxidoreductase), also known as ''electron transferring-flavoprotein dehydrogenase'', is a third entry point to the electron transport chain. It is an enzyme that accepts electrons from [[electron-transferring flavoprotein]] in the mitochondrial matrix, and uses these electrons to reduce ubiquinone.<ref>{{cite journal | vauthors = Ramsay RR, Steenkamp DJ, Husain M | title = Reactions of electron-transfer flavoprotein and electron-transfer flavoprotein: ubiquinone oxidoreductase | journal = The Biochemical Journal | volume = 241 | issue = 3 | pages = 883–892 | date = February 1987 | pmid = 3593226 | pmc = 1147643 | doi = 10.1042/bj2410883 }}</ref> This enzyme contains a [[Flavin group|flavin]] and a [4Fe–4S] cluster, but, unlike the other respiratory complexes, it attaches to the surface of the membrane and does not cross the lipid bilayer.<ref>{{cite journal | vauthors = Zhang J, Frerman FE, Kim JJ | title = Structure of electron transfer flavoprotein-ubiquinone oxidoreductase and electron transfer to the mitochondrial ubiquinone pool | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 103 | issue = 44 | pages = 16212–16217 | date = October 2006 | pmid = 17050691 | pmc = 1637562 | doi = 10.1073/pnas.0604567103 | doi-access = free | bibcode = 2006PNAS..10316212Z }}</ref>

{{NumBlk|:|<chem>ETF_{red}{} + Q -> ETF_{ox}{} + QH2</chem>|{{EquationRef|3}}}}

In mammals, this metabolic pathway is important in [[beta oxidation]] of [[fatty acid]]s and catabolism of [[amino acid]]s and [[choline]], as it accepts electrons from multiple [[acetyl-CoA]] dehydrogenases.<ref>{{cite journal | vauthors = Ikeda Y, Dabrowski C, Tanaka K | title = Separation and properties of five distinct acyl-CoA dehydrogenases from rat liver mitochondria. Identification of a new 2-methyl branched chain acyl-CoA dehydrogenase | journal = The Journal of Biological Chemistry | volume = 258 | issue = 2 | pages = 1066–1076 | date = January 1983 | pmid = 6401712 | doi = 10.1016/S0021-9258(18)33160-0 | url = http://www.jbc.org/cgi/reprint/258/2/1066 | url-status = live | doi-access = free | archive-url = https://web.archive.org/web/20070929111233/http://www.jbc.org/cgi/reprint/258/2/1066 | archive-date = 29 September 2007 }}</ref><ref>{{cite journal | vauthors = Ruzicka FJ, Beinert H | title = A new iron-sulfur flavoprotein of the respiratory chain. A component of the fatty acid beta oxidation pathway | journal = The Journal of Biological Chemistry | volume = 252 | issue = 23 | pages = 8440–8445 | date = December 1977 | pmid = 925004 | doi = 10.1016/S0021-9258(19)75238-7 | url = http://www.jbc.org/cgi/reprint/252/23/8440.pdf | url-status = live | doi-access = free | archive-url = https://web.archive.org/web/20070927135249/http://www.jbc.org/cgi/reprint/252/23/8440.pdf | archive-date = 2007-09-27 }}</ref> In plants, ETF-Q oxidoreductase is also important in the metabolic responses that allow survival in extended periods of darkness.<ref>{{cite journal | vauthors = Ishizaki K, Larson TR, Schauer N, Fernie AR, Graham IA, Leaver CJ | title = The critical role of Arabidopsis electron-transfer flavoprotein:ubiquinone oxidoreductase during dark-induced starvation | journal = The Plant Cell | volume = 17 | issue = 9 | pages = 2587–2600 | date = September 2005 | pmid = 16055629 | pmc = 1197437 | doi = 10.1105/tpc.105.035162 | bibcode = 2005PlanC..17.2587I }}</ref>