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 51 Kd (in mammals), which is the
second largest subunit of complex I and is a component of the iron-sulfur (IP)
fragment of the enzyme. It seems to bind to NAD, FMN, and a 4Fe-4S cluster.
The 51 Kd subunit is highly similar to [3,4]:
- Subunit α of Alcaligenes eutrophus NAD-reducing hydrogenase (gene hoxF)
which also binds to NAD, FMN, and a 4Fe-4S cluster.
- Subunit NQO1 of Paracoccus denitrificans NADH-ubiquinone oxidoreductase.
- Subunit F of Escherichia coli NADH-ubiquinone oxidoreductase (gene nuoF).
The 51 Kd subunit and the bacterial hydrogenase α subunit contains three
regions of sequence similarities. The first one most probably corresponds to
the NAD-binding site, the second to the FMN-binding site, and the third one,
which contains three cysteines, to the iron-sulfur binding region. We have
developed signature patterns for the FMN-binding and for the 4Fe-4S binding
regions.
PROSITE is copyright. It is produced by the Swiss Institute of
Bioinformatics (SIB). There are no restrictions on its use by non-profit
institutions as long as its content is in no way modified. Usage by and
for commercial entities requires a license agreement. For information
about the licensing scheme send an email to license@isb-sib.ch or
see: http://www.expasy.org/prosite/prosite_license.htm.
ExPASy Home page
CBR Canada