Glycerol phosphate shuttle

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The glycerol-3-phosphate shuttle is a mechanism that regenerates NAD+ from NADH, a by-product of glycolysis. Its importance in transporting reducing equivalents is secondary to the malate-aspartate shuttle.

Contents 1 Reaction 2 Reverse path 3 Function 4 See also 5 External links 6 General References

[edit] Reaction

In this shuttle, the enzyme called cytoplasmic glycerol-3-phosphate dehydrogenase converts dihydroxyacetone phosphate to glycerol 3-phosphate by oxidizing one molecule of NADH to NAD⁺ as in the following reaction:

[edit] Reverse path

Glycerol-3-phosphate gets converted back to dihydroxyacetone phosphate by a membrane-bound mitochondrial glycerophosphate dehydrogenase, this time reducing one molecule of enzyme-bound flavin adenine dinucleotide (FAD) to FADH₂. FADH₂ then reduces coenzyme Q (Ubiquinone to Ubiquinol) which enters into oxidative phosphorylization.

[edit] Function

The glycerol-3-phosphate shuttle allows the NADH synthesized in the cytosol by glycolysis to contribute to the oxidative phosphorylization pathway in the mitochondria to generate ATP.

[edit] See also

• Malate-aspartate shuttle
• Mitochondrial shuttle

[edit] External links

• http://web.indstate.edu/thcme/mwking/glycerol-phosphate-shuttle.html
• http://www.elmhurst.edu/~chm/vchembook/601glycolysissum.html
• http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-3/ch19_glycerol-shuttle.jpg

[edit] General References

• Stryer, Lubert; Berg, Jeremy Mark; Tymoczko, John L. (2007). Biochemistry. San Francisco: W. H. Freeman. ISBN 0-7167-8724-5.