NDUFA4 (NADH dehydrogenase (ubiquinone) 1 alpha subcomplex, 4), also known as MLRQ, is an 81 amino acid protein that localizes to the matrix side of the inner mitochondrial membrane and belongs to the complex I NDUFA4 subunit family. Existing as a subunit of the multi-protein membrane respiratory chain NADH dehydrogenase complex (Complex I), NDUFA4 functions as an accessory protein that facilitates the transfer of electrons from NADH to the respiratory chain. The gene encoding NDUFA7 maps to human chromosome 7, which houses over 1,000 genes and comprises nearly 5% of the human genome.