|Locus||Chr. 11 q11-q13.1|
It is the most important anaplerotic reaction that provides OAA precursor for the TCA during the time of exercise. The enzyme is a mitochondrial protein containing a biotin prosthetic group, requiring magnesium or manganese and acetyl CoA, and occurs in liver but not in muscle. It is an ATP-dependent enzyme. High levels of ADP inhibits the enzyme, while acetyl-CoA acts as an allosteric stimulator of the enzyme .
Pathways for Glucose Synthesis (Gluconeogenesis)
It is also the first pathway for the synthesis of phosphoenolpyruvate from pyruvate. Pyruvate is first converted by pyruvate carboxylase to oxaloacetate in the mitochondrion. During the reaction, one molecule of ATP is hydrolysed. The OAA is then decarboxylated and simultaneously phosphorylated, which is catalyzed by PEP carboxykinase to produce PEP in the cytosol. Transport of OAA from the mitochondrion to the cytosol is mediated by the malate/OAA shuttle.
A deficiency of pyruvate carboxylase can cause lactic acidosis as a result of lactate build up. Normally, excess pyruvate is shunted into gluconeogenesis via conversion of pyruvate into oxaloacetate, but because of the enzyme deficiency, excess pyruvate is converted into lactate instead. As a key role of gluconeogenesis is in the maintenance of blood sugar, deficiency of pyruvate carboxylase can also lead to hypoglycemia, among other things.
- ↑ Scrutton MC, Utter MF (1967) Pyruvate carboxylase. IX. Some properties of the activation by certain acyl derivatives of coenzyme A. J. Biol Chem. 242:1723-1735.
Ligases: carbon-carbon ligases (EC 6.4)
|Pyruvate carboxylase - Acetyl-CoA carboxylase - Propionyl-CoA carboxylase - Methylcrotonyl-CoA carboxylase - Polyketide synthase|
Carbohydrate metabolism: glycolysis/gluconeogenesis enzymes
|Glycolysis||Glucokinase/Hexokinase/Glucose 6-phosphatase - Glucose isomerase - Phosphofructokinase 1/Fructose 1,6-bisphosphatase - Aldolase - Triosephosphate isomerase - Glyceraldehyde 3-phosphate dehydrogenase - Phosphoglycerate kinase - Phosphoglycerate mutase - Enolase - Pyruvate kinase|
|Gluconeogenesis only||Pyruvate carboxylase - Phosphoenolpyruvate carboxykinase - from lactate (Cori cycle): Lactate dehydrogenase - from alanine (Alanine cycle): Alanine transaminase|
|Regulatory||Phosphofructokinase 2/Fructose 2,6-bisphosphatase - Bisphosphoglycerate mutase|
Metabolism: Citric acid cycle enzymes
|Cycle||Citrate synthase - Aconitase - Isocitrate dehydrogenase - Oxoglutarate dehydrogenase - Succinyl CoA synthetase|
Succinate dehydrogenase (SDHA, SDHB, SDHC, SDHD) - Fumarase - Malate dehydrogenase
|Anaplerotic||to acetyl-CoA: Pyruvate dehydrogenase complex (regulated by Pyruvate dehydrogenase kinase and Pyruvate dehydrogenase phosphatase) oxaloacetate: Pyruvate carboxylase - Aspartate transaminase|
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