Phosphoglycerate Mutase

Definition

Phosphoglycerate mutase is an enzyme that catalyzes the interconversion of 3-phosphoglycerate (3-PG) and 2-phosphoglycerate (2-PG) in the glycolytic pathway and gluconeogenesis. It plays a crucial role in regulating the flow of carbon through these central metabolic processes.

5 Must Know Facts For Your Next Test

1. Phosphoglycerate mutase catalyzes the reversible conversion of 3-phosphoglycerate to 2-phosphoglycerate, which is a key step in both glycolysis and gluconeogenesis.
2. The enzyme requires a cofactor, 2,3-bisphosphoglycerate, to facilitate the phosphate group transfer during the interconversion of 3-PG and 2-PG.
3. Phosphoglycerate mutase is allosterically regulated, with the binding of fructose-2,6-bisphosphate enhancing its activity and promoting glycolysis.
4. In gluconeogenesis, phosphoglycerate mutase catalyzes the reverse reaction, converting 2-PG to 3-PG, thereby facilitating the synthesis of glucose from non-carbohydrate precursors.
5. Mutations in the gene encoding phosphoglycerate mutase can lead to a rare metabolic disorder called glycogen storage disease type X, characterized by exercise intolerance and muscle cramps.

Review Questions

• Explain the role of phosphoglycerate mutase in the glycolytic pathway and its significance in energy production.
  • Phosphoglycerate mutase catalyzes the interconversion of 3-phosphoglycerate (3-PG) and 2-phosphoglycerate (2-PG) in the glycolytic pathway. This reaction is crucial because it facilitates the conversion of 3-PG to 2-PG, which is then further metabolized to produce ATP through substrate-level phosphorylation. By regulating the flow of carbon through this key step, phosphoglycerate mutase plays a vital role in the overall efficiency of glycolysis and the generation of cellular energy.
• Describe the function of phosphoglycerate mutase in the process of gluconeogenesis and its importance in maintaining blood glucose levels.
  • In the process of gluconeogenesis, phosphoglycerate mutase catalyzes the reverse reaction, converting 2-phosphoglycerate (2-PG) to 3-phosphoglycerate (3-PG). This step is crucial because it allows for the synthesis of glucose from non-carbohydrate precursors, such as amino acids and lactate. By facilitating this key reaction, phosphoglycerate mutase enables the body to maintain blood glucose levels and ensure a constant supply of glucose for essential cellular functions, particularly in situations where glucose is scarce or during prolonged fasting.
• Analyze the significance of the allosteric regulation of phosphoglycerate mutase and its implications for the coordination of glycolysis and gluconeogenesis.
  • Phosphoglycerate mutase is allosterically regulated, with the binding of fructose-2,6-bisphosphate enhancing its activity and promoting glycolysis. This regulatory mechanism is important because it allows the cell to sense the availability of glucose and other metabolic cues, and then adjust the activity of phosphoglycerate mutase accordingly. When glucose is abundant, the increased levels of fructose-2,6-bisphosphate activate phosphoglycerate mutase, thereby favoring glycolysis and the production of ATP. Conversely, when glucose is scarce, the allosteric regulation of phosphoglycerate mutase shifts to favor the reverse reaction, supporting gluconeogenesis and the synthesis of glucose from non-carbohydrate precursors. This coordinated regulation of glycolysis and gluconeogenesis by phosphoglycerate mutase is crucial for maintaining cellular energy homeostasis and blood glucose levels.

Related terms

Glycolysis: The metabolic pathway that converts glucose into pyruvate, generating a small amount of ATP in the process.

Gluconeogenesis: The metabolic pathway that synthesizes glucose from non-carbohydrate precursors, such as amino acids and lactate.

3-Phosphoglycerate (3-PG): An intermediate in glycolysis and gluconeogenesis that is converted to 2-phosphoglycerate by phosphoglycerate mutase.