- Electron-transferring flavoprotein
Electron transfer flavoproteins (ETFs) serve as specific electron acceptors for primary
dehydrogenases, transferring the electrons to terminal respiratory systems such as electron-transferring-flavoprotein dehydrogenase. They can be functionally classified into constitutive, "housekeeping" ETFs, mainly involved in the oxidation of fatty acids (Group I), and ETFs produced by some prokaryotes under specific growth conditions, receiving electrons only from the oxidation of specific substrates (Group II).cite journal |author=Weidenhaupt M, Rossi P, Beck C, Fischer HM, Hennecke H |title=Bradyrhizobium japonicum possesses two discrete sets of electron transfer flavoprotein genes: fixA, fixB and etfS, etfL |journal=Arch. Microbiol. |volume=165 |issue=3 |pages=169–78 |year=1996 |pmid=8599534 |doi=]
ETFs are heterodimeric proteins composed of an alpha and beta subunit, and contain an FAD cofactor and AMP.cite journal |author=Tsai MH, Saier MH |title=Phylogenetic characterization of the ubiquitous electron transfer flavoprotein families ETF-alpha and ETF-beta |journal=Res. Microbiol. |volume=146 |issue=5 |pages=397–404 |year=1995 |pmid=8525056 |doi=] cite journal |author=Roberts DL, Frerman FE, Kim JJ |title=Three-dimensional structure of human electron transfer flavoprotein to 2.1-A resolution |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=93 |issue=25 |pages=14355–60 |year=1996 |pmid=8962055 |doi=] ETF consists of three domains: domains I and II are formed by the N- and C-terminal portions of the alpha subunit, respectively, while domain III is formed by the beta subunit. Domains I and III share an almost identical alpha-beta-alpha sandwich fold, while domain II forms an alpha-beta-alpha sandwich similar to that of bacterial
flavodoxins. FAD is bound in a cleft between domains II and III, while domain III binds the AMP molecule. Interactions between domains I and III stabilise the protein, forming a shallow bowl where domain II resides.
Electron transport chain
* Pfam database - Electron-transferring flavoprotein. http://pfam.sanger.ac.uk/family?entry=PF00766
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