malate-aspartate shuttle

malate-aspartate shuttle
a mechanism for transferring electrons into mitochondria from the cytosol of red fibers of skeletal muscle, heart, and the brain, involving cytosolic and mitochondrial forms of the enzymes malate dehydrogenase and aspartate transaminase, and two transmembrane carriers. Electrons from cytosolic NADH are used to reduce oxaloacetate to malate, which enters the mitochondrial matrix and donates electrons to NAD+, becoming reoxidized to oxaloacetate. To return to the cytosol, oxaloacetate is first transaminated to form aspartate, which can traverse the membrane; once in the cytosol it is deaminated to oxaloacetate.

Medical dictionary. 2011.

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