InterPro domain: IPR002023

Respiratory-chain NADH dehydrogenase ( 7.1.1.2 ) [ 1 ] (also known as complex I or NADH-ubiquinone oxidoreductase) is an oligomeric enzymatic complex located in the inner mitochondrial membrane which also seems to exist in the chloroplast and in cyanobacteria (as a NADH-plastoquinone oxidoreductase). Among the 25 to 30 polypeptide subunits of this bioenergetic enzyme complex there is one with a molecular weight of 24 Kd (in mammals), which is a component of the iron-sulfur (IP) fragment of the enzyme. It seems to bind a 2Fe-2S iron-sulfur cluster. The 24 Kd subunit is nuclear encoded, as a precursor form with a transit peptide in mammals, and in Neurospora crassa.The 24 Kd subunit is highly similar to [ 2 , 3 ]: Subunit E of Escherichia coli NADH-ubiquinone oxidoreductase (gene nuoE) and Subunit NQO2 of Paracoccus denitrificans NADH-ubiquinone oxidoreductase.

1. The respiratory-chain NADH dehydrogenase (complex I) of mitochondria. Eur. J. Biochem. 197, 563-76
2. Conservation of sequences of subunits of mitochondrial complex I and their relationships with other proteins. Biochim. Biophys. Acta 1140, 105-34
3. The gene locus of the proton-translocating NADH: ubiquinone oxidoreductase in Escherichia coli. Organization of the 14 genes and relationship between the derived proteins and subunits of mitochondrial complex I. J. Mol. Biol. 233, 109-22