Calcium-dependent NAD(P)H dehydrogenase. Binds calcium ions (By similarity). Alternative NADH-ubiquinone oxidoreductase which catalyzes the oxidation of mitochondrial NADH does not translocate protons across the inner mitochondrial membrane. a quinone + H(+) + NADH = a quinol + NAD(+) a ubiquinone + H(+) + NADH = a ubiquinol + NAD(+) Binds 1 FAD per subunit. Activity is calcium-dependent with a more pronounced effect at higher pH. Belongs to the NADH dehydrogenase family.