An electron transfer flavoprotein (ETF) or electron transfer flavoprotein complex (CETF) is a
flavoprotein
Flavoproteins are proteins that contain a nucleic acid derivative of riboflavin.
Flavoproteins are involved in a wide array of biological processes, including removal of radicals contributing to oxidative stress, photosynthesis, and DNA repair ...
located on the matrix face of the inner mitochondrial membrane and functions as a specific electron acceptor for primary
dehydrogenase
A dehydrogenase is an enzyme belonging to the group of oxidoreductases that oxidizes a substrate by reducing an electron acceptor, usually NAD+/NADP+ or a flavin coenzyme such as FAD or FMN. Like all catalysts, they catalyze reverse as well as f ...
s, transferring the electrons to terminal respiratory systems such as
electron-transferring-flavoprotein dehydrogenase
Electron-transferring-flavoprotein dehydrogenase (''ETF dehydrogenase'' or ''electron transfer flavoprotein-ubiquinone oxidoreductase'', ) is an enzyme that transfers electrons from electron-transferring flavoprotein in the mitochondrial matrix, t ...
. 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).
ETFs are heterodimeric proteins composed of an alpha and beta subunit (
ETFA
The human ETFA gene encodes the Electron-transfer-flavoprotein, alpha subunit, also known as ETF-α. Together with Electron-transfer-flavoprotein, beta subunit, encoded by the 'ETFB' gene, it forms the heterodimeric electron transfer flavoprotein ...
and
ETFB
The human ETFB gene encodes the Electron-transfer-flavoprotein, beta subunit, also known as ETF-β. Together with Electron-transfer-flavoprotein, alpha subunit, encoded by the 'ETFA' gene, it forms the heterodimeric Electron transfer flavoprotein ...
), and contain an
FAD
A fad or trend is any form of collective behavior that develops within a culture, a generation or social group in which a group of people enthusiastically follow an impulse for a short period.
Fads are objects or behaviors that achieve short- ...
cofactor and
AMP #REDIRECT Amp
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.
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
flavodoxin Flavodoxins (Fld) are small, soluble electron-transfer proteins. Flavodoxins contains flavin mononucleotide as prosthetic group. The structure of flavodoxin is characterized by a five-stranded parallel beta sheet, surrounded by five alpha helices. T ...
s. 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.
Mutation in ETFs can lead to deficiency of passing reducing equivalent of FADH
2 to electron transport chain, causing
Glutaric acidemia type 2
Glutaric acidemia type 2 is an autosomal recessive metabolic disorder that is characterised by defects in the ability of the body to use proteins and fats for energy. Incompletely processed proteins and fats can build up, leading to a dangerous c ...
See also
*
Electron transport chain
An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples th ...
*
Electron-transferring-flavoprotein dehydrogenase
Electron-transferring-flavoprotein dehydrogenase (''ETF dehydrogenase'' or ''electron transfer flavoprotein-ubiquinone oxidoreductase'', ) is an enzyme that transfers electrons from electron-transferring flavoprotein in the mitochondrial matrix, t ...
*
Glutaric acidemia type 2
Glutaric acidemia type 2 is an autosomal recessive metabolic disorder that is characterised by defects in the ability of the body to use proteins and fats for energy. Incompletely processed proteins and fats can build up, leading to a dangerous c ...
*
Metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
*
Microbial metabolism
Microbial metabolism is the means by which a microbe obtains the energy and nutrients (e.g. carbon) it needs to live and reproduce. Microbes use many different types of metabolic strategies and species can often be differentiated from each other ...
*
Oxidative phosphorylation
Oxidative phosphorylation (UK , US ) or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine tri ...
References
{{reflist
External links
Pfam entry for Electron transfer flavoprotein domainPfam entry for Electron transfer flavoprotein FAD-binding domain
Proteins