Question: how cytosolic nadh is oxidized in the mitochondria?
Answer: In plant mitochondria, cytosolic NADH can be oxidized either by an external NADH dehydrogenase or by a redox shuttle (14), whereas in the mitochondrial matrix, NADH can be oxidized by the proton-translocating complex I or by an alternative, nontranslocating, internal NADH dehydrogenase (9).