{PDOC00555}
{PS00644; COMPLEX1_51K_1}
{PS00645; COMPLEX1_51K_2}
{BEGIN}
*****************************************************************
* Respiratory-chain NADH dehydrogenase 51 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 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 alpha 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 alpha 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.

-Consensus pattern: G-[AM]-G-[AR]-Y-[LIVM]-C-G-[DE](2)-[STA](2)-[LIM](2)-[EN]-
                    S
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Consensus pattern: E-[ST]-C-G-x-C-x-P-C-R-x-G
                    [The 3 C's may be 4Fe-4S ligands]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: May 2004 / Text revised.

[ 1] Ragan C.I.
     Curr. Top. Bioenerg. 15:1-36(1987).
[ 2] Weiss H., Friedrich T., Hofhaus G., Preis D.
     "The respiratory-chain NADH dehydrogenase (complex I) of
     mitochondria."
     Eur. J. Biochem. 197:563-576(1991).
     PubMed=2029890
[ 3] Fearnley I.M., Walker J.E.
     "Conservation of sequences of subunits of mitochondrial complex I and
     their relationships with other proteins."
     Biochim. Biophys. Acta 1140:105-134(1992).
     PubMed=1445936
[ 4] Weidner U., Geier S., Ptock A., Friedrich T., Leif H., Weiss H.
     "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. 233:109-122(1993).
     PubMed=7690854

--------------------------------------------------------------------------------
PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and
distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives
(CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html
--------------------------------------------------------------------------------

{END}