Description | NADH:ubiquinone oxidoreductase (complex I) ( ) is a respiratory-chain enzyme that catalyses the transfer of two electrons from NADH to ubiquinone in a reaction that is associated with proton translocation across the membrane (NADH + ubiquinone = NAD+ + ubiquinol) [ ]. Complex I is a major source of reactive oxygen species (ROS) that are predominantly formed by electron transfer from FMNH(2). Complex I is found in bacteria, cyanobacteria (as a NADH-plastoquinone oxidoreductase), archaea [], mitochondria, and in the hydrogenosome, a mitochondria-derived organelle. In general, the bacterial complex consists of 14 different subunits, while the mitochondrial complex contains homologues to these subunits in addition to approximately 31 additional proteins [].Among the many polypeptide subunits that make up complex I, there is one with a molecular weight of 51kDa (in mammals), which is the second largest subunit of complex I and is a component of the iron-sulphur (IP) fragment of the enzyme. It seems to bind to NAD, FMN, and a 2Fe-2S cluster. The 51kDa subunit and the bacterial hydrogenase alpha subunit contain 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-sulphur binding region. | Name | NADH:ubiquinone oxidoreductase, 51kDa subunit, conserved site |
Short Name | NADH-UbQ_OxRdtase_51kDa_CS | Type | Conserved_site |