NDUFS5 gene is a member of the NADH dehydrogenase (ubiquinone) iron-sulfur protein family. The encoded protein is a subunit of the NADH:ubiquinone oxidoreductase (complex I),the first enzyme complex in the electron transport chain located in the inner mitochondrial membrane. The NDUFS5 mRNA is expressed ubiquitously in human tissues,with a relative higher expression in human heart,skeletal muscle,liver,kidney and fetal heart . The NDUFS5 (15 kDa) subunit located at mitochondrion and contains two C-X9-C motifs that are predicted to form a helix-coil-helix structure,permitting the formation of intramolecular disulfide bonds . NDUFS5 antibody is capable of detecting the 15 kDa protein in Western blotting.