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PROSITE documentation PDOC00858Respiratory-chain NADH dehydrogenase 20 Kd subunit signature
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PURL: https://purl.expasy.org/prosite/documentation/PDOC00858
Respiratory-chain NADH dehydrogenase (EC 1.6.5.3) [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 20 Kd (in mammals) [3], which is a component of the iron-sulfur (IP) fragment of the enzyme. It seems to bind a 4Fe-4S iron-sulfur cluster. The 20 Kd subunit 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 (gene psbG).
- Chloroplast encoded in various higher plants (gene ndhK or psbG).
The 20 Kd subunit is highly similar to [4]:
- Synechocystis strain PCC 6803 proteins psbG1 and psbG2.
- Subunit B of Escherichia coli NADH-ubiquinone oxidoreductase (gene nuoB).
- Subunit NQO6 of Paracoccus denitrificans NADH-ubiquinone oxidoreductase.
- Subunit 7 of Escherichia coli formate hydrogenlyase (gene hycG).
- Subunit I of Escherichia coli hydrogenase-4 (gene hyfI).
As as signature pattern we selected a highly conserved region, located in the central section of this subunit and which contains a conserved cysteine that is probably involved in the binding of the 4Fe-4S center.
Last update:December 2004 / Pattern and text revised.
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PROSITE method (with tools and information) covered by this documentation:
| 1 | Authors | Ragan C.I. |
| Source | Curr. Top. Bioenerg. 15:1-36(1987). |
| 2 | Authors | Weiss H. Friedrich T. Hofhaus G. Preis D. |
| Title | The respiratory-chain NADH dehydrogenase (complex I) of mitochondria. | |
| Source | Eur. J. Biochem. 197:563-576(1991). | |
| PubMed ID | 2029890 |
| 3 | Authors | Arizmendi J.M. Runswick M.J. Skehel J.M. Walker J.E. |
| Title | NADH: ubiquinone oxidoreductase from bovine heart mitochondria. A fourth nuclear encoded subunit with a homologue encoded in chloroplast genomes. | |
| Source | FEBS Lett. 301:237-242(1992). | |
| PubMed ID | 1577158 |
| 4 | Authors | Weidner U. Geier S. Ptock A. Friedrich T. Leif H. Weiss H. |
| Title | 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. | |
| Source | J. Mol. Biol. 233:109-122(1993). | |
| PubMed ID | 7690854 |
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