Accessory subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I), that is believed not to be involved in catalysis. Complex I functions in the transfer of electrons from NADH to the respiratory chain. The immediate electron acceptor for the enzyme is believed to be ubiquinone. Complex I is composed of 45 different subunits (PubMed:12611891, PubMed:27626371). Interacts with BCAP31 (PubMed:31206022). The interaction with BCAP31 mediates mitochondria localization. Ubiquitous. The disease is caused by variants affecting the gene represented in this entry. The disease may be caused by variants affecting the gene represented in this entry. Belongs to the complex I NDUFB11 subunit family.