This gene encodes a member of the Mrp/NBP35 ATP-binding proteins family. The encoded protein is required for the assembly of the respiratory chain NADH dehydrogenase (complex I), an oligomeric enzymatic complex located in the inner mitochondrial membrane. The respiratory complex I consists of 45 subunits and 8 iron-sulfur (Fe/S) clusters. This protein is an Fe/S protein that plays a critical role in the assembly of respiratory complex I, likely by transferring Fe/S into the Fe/S-containing complex I subunits. Mutations in this gene cause mitochondrial complex I deficiency. Alternatively spliced transcript variants encoding distinct isoforms have been identified.