NADH:ubiquinone oxidoreductase, chain 2 (IPR003917)

Short name: NADH_UbQ_OxRdtase_chain2

Overlapping homologous superfamilies


Family relationships



NADH:ubiquinone oxidoreductase (complex I) (EC: 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) [PMID: 1470679]. 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 [PMID: 10940377], 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 [PMID: 18394423].

This entry represents subunit 2 (ND2 or chain 2) from NADH:ubiquinone oxidoreductase (complex I). Defects in the ND2 gene are one of the causes of Leber's hereditary optic neuropathy, a maternally inherited disease resulting in acute bilateral blindness due to retinal degeneration, predominantly in young men [PMID: 1900003, PMID: 1732158]. Cardiac conduction defects and neurological defects have also been described, resulting in optic nerve degeneration and cardiac dysrhythmia [PMID: 3201231]. The clinical manifestations of this disease are thought to be the product of an overall decrease in mitochondrial energy production, rather than the result of a defect in a specific mitochondrial enzyme [PMID: 1732158]. Further research has shown that a point mutation in ND2 is a potential risk factor for Alzheimer's disease [PMID: 1370613].

GO terms

Biological Process

GO:0006120 mitochondrial electron transport, NADH to ubiquinone
GO:0055114 oxidation-reduction process

Molecular Function

GO:0008137 NADH dehydrogenase (ubiquinone) activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.