 The generation of ATP by the mitochondrion from cytosolic NADH relies on the malate @-@ aspartate shuttle ( and to a lesser extent , the glycerol @-@ phosphate shuttle ) because the inner mitochondrial membrane is impermeable to NADH and NAD + . Instead of transferring the generated NADH , a malate dehydrogenase enzyme converts oxaloacetate to malate , which is translocated to the mitochondrial matrix . Another malate dehydrogenase @-@ catalyzed reaction occurs in the opposite direction , producing oxaloacetate and NADH from the newly transported malate and the mitochondrion 's interior store of NAD + . A transaminase converts the oxaloacetate to aspartate for transport back across the membrane and into the intermembrane space . 
