PROSITE documentation PDOC00468
Respiratory-chain NADH dehydrogenase 30 Kd subunit signature


Respiratory-chain NADH dehydrogenase (EC [1,2] (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 30 Kd (in mammals) which has been found to be:

  • Nuclear encoded, as a precursor form with a transit peptide in mammals, and in Neurospora crassa.
  • Mitochondrial encoded in Paramecium (protein P1), and in the slime mold Dictyostelium discoideum (ORF 209).
  • Chloroplast encoded in various higher plants (ORF 159).

It is also present in bacteria:

  • In the cyanobacteria Synechocystis strain PCC 6803 (gene ndhJ).
  • Subunit C of Escherichia coli NADH-ubiquinone oxidoreductase (gene nuoC).
  • Subunit NQO5 of Paracoccus denitrificans NADH-ubiquinone oxidoreductase.

This protein, in its mature form, consists of from 157 to 266 amino acid residues. The best conserved region is located in the C-terminal section and can be used as a signature pattern.

Last update:

December 2001 / Pattern and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

COMPLEX1_30K, PS00542; Respiratory chain NADH dehydrogenase 30 Kd subunit signature  (PATTERN)


1AuthorsRagan C.I.
SourceCurr. Top. Bioenerg. 15:1-36(1987).

2AuthorsWeiss H. Friedrich T. Hofhaus G. Preis D.
TitleThe respiratory-chain NADH dehydrogenase (complex I) of mitochondria.
SourceEur. J. Biochem. 197:563-576(1991).
PubMed ID2029890

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