This subunit is part of the mitochondrial NADH:ubiquinone oxidoreductase (complex I). It carries mitochondrial import sequences [1].

1: Definition of the nuclear encoded protein composition of bovine heart mitochondrial complex I. Identification of two new subunits. Carroll J, Shannon RJ, Fearnley IM, Walker JE, Hirst J; J Biol Chem. 2002;277:50311-50317. PMID:12381726