MopB_Res_Cmplx1_Nad11_M: Mitochondrial-encoded NADH-quinone oxidoreductase/respiratory complex I, the second domain of the Nad11/75-kDa subunit of some protists. NADH-quinone oxidoreductase is the first energy-transducting complex in the respiratory chain and functions as a redox pump that uses the redox energy to translocate H+ ions across the membrane, resulting in a significant contribution to energy production. The nad11 gene codes for the largest (75-kDa) subunit of the mitochondrial NADH-quinone oxidoreductase, it constitutes the electron input part of the enzyme, or the so-called NADH dehydrogenase fragment. The Nad11 subunit is made of two domains: the first contains three binding sites for FeS clusters (the fer2 domain), the second domain (this CD), is of unknown function or, as postulated, has lost an ancestral formate dehydrogenase activity that became redundant during the evolution of the complex I enzyme. Although only vestigial sequence evidence remains of a molybdopterin binding site, this protein domain belongs to the molybdopterin_binding (MopB) superfamily of proteins.
Jiyao W et al.(2023). "The conserved domain database in 2023.",