Alternative NADH-ubiquinone oxidoreductase which catalyzes the oxidation of mitochondrial NADH does not translocate protons across the inner mitochondrial membrane (By similarity). Calcium-dependent NAD(P)H dehydrogenase. Binds calcium ions. 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. Optimum pH is 6.8-7.2 with NADPH as substrate and 6.8 with NADH as substrate. Expressed in seedlings, roots, cotyledons, leaves, stems, buds and flowers. Belongs to the NADH dehydrogenase family.