ND5 Gene (MT-ND5): Function, Mutations, and Associated Diseases

MT-ND5 encodes the NADH dehydrogenase subunit 5, a core subunit of mitochondrial Complex I (NADH:ubiquinone oxidoreductase). Complex I is the first enzyme of the oxidative phosphorylation (OXPHOS) system, catalyzing the transfer of electrons from NADH to ubiquinone and contributing to the proton gradient across the inner mitochondrial membrane. ND5 is one of the seven mitochondrial-encoded subunits of Complex I and is essential for its assembly and catalytic activity. Mutations in MT-ND5 are associated with a spectrum of mitochondrial disorders, including Leber hereditary optic neuropathy (LHON), mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), Leigh syndrome, and other complex I deficiency phenotypes. Somatic mutations in MT-ND5 have also been reported in various cancers, potentially influencing tumor metabolism.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Oxidative phosphorylation (KEGG: hsa00190)

• Metabolic pathways (KEGG: hsa01100)

• Thermogenesis (KEGG: hsa04714)

• Parkinson disease (KEGG: hsa05012)

• Huntington disease (KEGG: hsa05016)

• Alzheimer disease (KEGG: hsa05010)

The ND5 protein (UniProt P03915) is a 603-amino acid hydrophobic subunit of mitochondrial Complex I. It is embedded in the inner mitochondrial membrane and contributes to the proton translocation machinery. ND5 is part of the membrane arm of Complex I, where it participates in the conformational changes that drive proton pumping. The protein has 14 transmembrane helices and is essential for the assembly and stability of the holoenzyme. Defects in ND5 lead to impaired electron transfer and proton gradient generation, resulting in mitochondrial dysfunction. The protein is synthesized within mitochondria and requires the mitochondrial translation machinery for its production.