{PDOC00858} {PS01150; COMPLEX1_20K} {BEGIN} **************************************************************** * Respiratory-chain NADH dehydrogenase 20 Kd subunit signature * **************************************************************** 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. -Consensus pattern: [GN]-x-[DE]-[KRHST]-[LIVMFA]-[LIVMF]-P-[IV]-D-[LIVMFYWA]- [LIVMFYWK]-x-P-x-C-P-[PT] [The C may be a 4Fe-4S ligand] -Sequences known to belong to this class detected by the pattern: ALL. -Other sequence(s) detected in Swiss-Prot: NONE. -Last update: December 2004 / Pattern and 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] Arizmendi J.M., Runswick M.J., Skehel J.M., Walker J.E. "NADH: ubiquinone oxidoreductase from bovine heart mitochondria. A fourth nuclear encoded subunit with a homologue encoded in chloroplast genomes." FEBS Lett. 301:237-242(1992). PubMed=1577158 [ 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}