Glycerol phosphate shuttle
- Glycerol phosphate shuttle
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.
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:
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.[ This reaction is irreversible.][cite journal |author=Shen W, Wei Y, Dauk M, "et al" |title=Involvement of a glycerol-3-phosphate dehydrogenase in modulating the NADH/NAD+ ratio provides evidence of a mitochondrial glycerol-3-phosphate shuttle in Arabidopsis |journal=Plant Cell |volume=18 |issue=2 |pages=422–41 |year=2006 |month=February |pmid=16415206 |pmc=1356549 |doi=10.1105/tpc.105.039750] ]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.[cite book |author=Stryer, Lubert; Berg, Jeremy Mark; Tymoczko, John L. |title=Biochemistry |publisher=W. H. Freeman |location=San Francisco |year=2007 |pages= |isbn=0-7167-8724-5 |oclc= |doi= |url=http://bcs.whfreeman.com/biochem6/default.asp?s=&n=&i=&v=&o=&ns=0&uid=0&rau=0] It has been found in animal, fungus, and plant.]ee also
* Malate-aspartate shuttle
* Mitochondrial shuttle
References
External links
* http://www.elmhurst.edu/~chm/vchembook/601glycolysissum.html (describes the shuttle in the context of glykolysis)
* http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-3/ch19_glycerol-shuttle.jpg (illustration of the two reactions)
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Look at other dictionaries:
glycerol phosphate shuttle — a cyclic mechanism for transferring electrons from cytosolic NADH to the mitochondrial electron transport chain and thus to oxygen, acting by means of enzyme catalyzed redox reactions that interconvert glycerol 3 phosphate and dihydroxyacetone… … Medical dictionary
glycerol phosphate — (L )glycerol 3 phosphate an intermediate in the glycerol phosphate shuttle, in the utilization of glycerol, and in the biosynthesis of lipids … Medical dictionary
Glycerol-3-phosphate dehydrogenase — protein Name=glycerol 3 phosphate dehydrogenase 1 (soluble) caption= width= HGNCid=4455 Symbol=GPD1 AltSymbols= EntrezGene=2819 OMIM=138420 RefSeq=NM 005276 UniProt=P21695 PDB= ECnumber=1.1.1.8 Chromosome=12 Arm=q Band=12 LocusSupplementaryData=… … Wikipedia
glycerol-3-phosphate dehydrogenase — α Glycerol phosphate dehydrogenase; 3 phosphoglycerol dehydrogenase; a flavoenzyme that catalyzes the interconversion of dihydroxyacetone phosphate and sn glycerol 3 phosphate, with the participation of NAD+; its action provides the glycerol… … Medical dictionary
glycerol-3-phosphate dehydrogenase (NAD+) — glyc·er·ol 3 phos·phate de·hy·dro·gen·ase (NAD+) (glisґər ol fosґfāt de hiґdro jən ās) [EC 1.1.1.8] a cytosolic enzyme of the oxidoreductase class that catalyzes the oxidation of glycerol 3 phosphate to dihydroxyacetone… … Medical dictionary
Glycerol 3-phosphate — Chembox new ImageFile = glycerol 3 phosphate.png ImageSize = 150px IUPACName = 1,2,3 Propanetriol, 1 (dihydrogen phosphate) OtherNames = Glycerol 1 phosphate Glycerophosphate α glycerolphosphate Section1 = Chembox Identifiers CASNo = 57 03 4… … Wikipedia
Mitochondrial shuttle — The mitochondrial shuttles are systems used to transport reducing agents across the inner mitochondrial membrane. NADH cannot cross the membrane, but it can reduce another molecule that can cross the membrane, so that its electrons can reach the… … Wikipedia
Malate-aspartate shuttle — Diagram Illustrating the Malate Asparate Shuttle Pathway The malate aspartate shuttle (sometimes also the malate shuttle) is a biochemical system for translocating electrons produced during glycolysis across the semipermeable inner membrane of… … Wikipedia
dihydroxyacetone phosphate — an intermediate in glycolysis, the glycerol phosphate shuttle, and the biosynthesis of carbohydrates and of lipids … Medical dictionary
shuttle — A going back and forth regularly; used in respect to certain transport processes across a biomembrane. glycerophosphate s. a mechanism for the transfer of reducing equivalents from the cytosol into the mitochondria; NADH is used to synthesize … Medical dictionary
