Malate-Aspartate Shuttle

Notes

Location: Heart, Liver

Cytoplasmic NADH reduces oxaloacetate into malate. This can then enter the mitochondria via an antiporter (malate comes in, a-Ketoglutarate goes out).

This then interacts with an enzyme called 

Matrix malate dehydrogenase which converts malate→ oxaloacetate and regenerates NADH in the inner mitochondrial space. 

Now, oxaloacetate needs to make its way back to the cytosol. To do this, it gets converted into aspartate and pumped out of another antiporter that shuttled glutamate in and aspartate out. 

In the cytosol, aspartate becomes oxaloacete again, and a-ketogluterate becomes glutamate to keep the system running. 

This system regenerates NADH directly in the matrix, so these electrons and H+ enter at Complex I. This allows for more proton pumping and ultimately a greater ATP yield.