Gluconeogenesis: Difference between revisions

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Alexander Berchansky

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 <StructureSection load='2y3i' size='350' side='right' scene='' caption='Human phosphoglycerate kinase complex with phosphoglyceric acid, ADP (stick model) AlF4-, Cl- and Mg+2 ions (green) (PDB code [[2y3i]])'>
-'''Under development!'''
+Gluconeogenesis ([https://en.wikipedia.org/wiki/Gluconeogenesis]) is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. In humans the main gluconeogenic precursors are lactate, <scene name='92/925544/Cv/1'>glycerol</scene> (which is a part of the triglyceride molecule), alanine and glutamine. Other glucogenic amino acids and all [[Citric Acid Cycle]] intermediates (through conversion to oxaloacetate) can also function as substrates for gluconeogenesis. See also [[Cori cycle]] and [[Glyoxylate cycle]].
-Gluconeogenesis is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. In humans the main gluconeogenic precursors are lactate, <scene name='92/925544/Cv/1'>glycerol</scene> (which is a part of the triglyceride molecule), alanine and glutamine. Other glucogenic amino acids and all [[Citric Acid Cycle]] intermediates (through conversion to oxaloacetate) can also function as substrates for gluconeogenesis.
 <scene name='39/392339/Cv1/10'>Lactate</scene> is transported back to the liver where it is converted into <scene name='39/392339/Cv1/11'>pyruvate</scene> by the [[Cori cycle]] using the enzyme [[lactate dehydrogenase]]. <scene name='Lactate_Dehydrogenase/Cv/4'>Interconversion of pyruvate and lactate acid</scene>. Pyruvate, the first designated substrate of the gluconeogenic pathway, can then be used to generate glucose.
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 '''4)''' <scene name='43/430893/Cv/3'>Oxaloacetate</scene> is decarboxylated and then phosphorylated to form <scene name='39/392339/Cv1/8'>phosphoenolpyruvate</scene> using the enzyme [[PEPCK]]. A molecule of GTP is hydrolyzed to GDP during this reaction.
-The next steps in the reaction are the same as reversed glycolysis. However, fructose 1,6-bisphosphatase converts fructose 1,6-bisphosphate to fructose 6-phosphate, using one water molecule and releasing one phosphate (in glycolysis, phosphofructokinase 1 converts F6P and ATP to F1,6BP and ADP). This is also the rate-limiting step of gluconeogenesis.
+The next steps in the reaction are the same as reversed glycolysis. However, [[fructose 1,6-bisphosphatase]] converts <scene name='39/392339/Cv1/2'>fructose 1,6-bisphosphate</scene> to <scene name='92/925544/Cv/5'>fructose 6-phosphate</scene>, using one water molecule and releasing one phosphate (in glycolysis, phosphofructokinase 1 converts F6P and ATP to F1,6BP and ADP). This is also the rate-limiting step of gluconeogenesis.
+<scene name='39/392339/Cv/4'>Glucose-6-phosphate</scene> is formed from <scene name='39/392339/Cv1/1'>fructose-6-phosphate</scene> by [[phosphoglucoisomerase]] (the reverse of step 2 in glycolysis). Glucose-6-phosphate can be used in other metabolic pathways or dephosphorylated to free glucose.
+The final gluconeogenesis, the formation of glucose, occurs in the lumen of the endoplasmic reticulum, where <scene name='39/392339/Cv/4'>glucose-6-phosphate</scene> is hydrolyzed by glucose-6-phosphatase to produce <scene name='39/392339/Cv/3'>glucose</scene> and release an inorganic phosphate.
 </StructureSection>
 == References ==
 <references/>