Glycerol Phosphate Shuttle
The glycerol phosphate shuttle is a secondary mechanism for the transport of electrons from cytosolic NADH to mitochondrial carriers of the oxidative phosphorylation pathway. The primary cytoplasmic NADH electron shuttle is the malate-aspartate shuttle. Two enzymes are involved in this shuttle. One is the cytosolic version of the enzyme glycerol-3-phosphate dehydrogenase (glycerol-3-PDH) which has as one substrate, NADH. The second is is the mitochondrial form of the enzyme which has as one of its’ substrates, FAD+. The net result is that there is a continual conversion of the glycolytic intermediate, DHAP and glycerol-3-phosphate with the concomitant transfer of the electrons from reduced cytosolic NADH to mitochondrial oxidized FAD+. Since the electrons from mitochondrial FADH2 feed into the oxidative phosphorylation pathway at coenzyme Q (as opposed to NADH-ubiquinone oxidoreductase [complex I]) only 2 moles of ATP will be generated from glycolysis. G3PDH is glyceraldehyde-3-phoshate dehydrogenase.
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- Salway, J.G. (2004) Metabolism at a glance (3 rd ed.). Alden, Mass. : Blackwell Pub.