PROSITE documentation PDOC00554Respiratory-chain NADH dehydrogenase 75 Kd subunit signatures
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 75 Kd (in mammals), which is the largest subunit of complex I and is a component of the iron-sulfur (IP) fragment of the enzyme. It seems to bind to two 4Fe-4S clusters (called N-3 and N-4).
The 75 Kd subunit is highly similar to [3,4]:
- Subunit γ of Alcaligenes eutrophus NAD-reducing hydrogenase (gene hoxU) which also binds two 4Fe-4S cluster.
- Subunit NQO3 of Paracoccus denitrificans NADH-ubiquinone oxidoreductase.
- Subunit G of Escherichia coli NADH-ubiquinone oxidoreductase (gene nuoG).
The 75 Kd subunit and the bacterial hydrogenase γ subunit contains three conserved clusters of cysteine residues which are most probably involved in the binding of the iron-sulfur clusters. We have developed signature patterns for these three regions.
Last update:December 2004 / Pattern and text revised.
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PROSITE methods (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 | Fearnley I.M. Walker J.E. |
| Title | Conservation of sequences of subunits of mitochondrial complex I and their relationships with other proteins. | |
| Source | Biochim. Biophys. Acta 1140:105-134(1992). | |
| PubMed ID | 1445936 |
| 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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