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. Binds 1 FAD per subunit. Complex I is composed of 45 different subunits. This a component of the hydrophobic protein fraction. Belongs to the complex I NDUFA10 subunit family.