PGD2
PFKM
PFKM (Phosphofructokinase, Muscle Type) is an enzyme that plays a crucial role in the glycolytic pathway, which is the metabolic pathway that converts glucose into pyruvate, generating energy in the form of ATP. PFKM is one of the three isoforms of phosphofructokinase, the others being PFKL (liver type) and PFKP (platelet type). This enzyme is encoded by the PFKM gene in humans.
Structure[edit | edit source]
PFKM is a tetrameric enzyme, meaning it is composed of four subunits. Each subunit is encoded by the PFKM gene, and the tetramer can be composed of different combinations of the muscle, liver, and platelet isoforms, depending on the tissue type. The structure of PFKM allows it to be regulated by various allosteric effectors, which can either activate or inhibit its activity.
Function[edit | edit source]
PFKM catalyzes the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate, using ATP as the phosphate donor. This reaction is a key regulatory step in the glycolytic pathway and is considered the first committed step of glycolysis. The activity of PFKM is regulated by several factors, including:
- ATP: High levels of ATP inhibit PFKM, as ATP is both a substrate and an allosteric inhibitor.
- AMP: High levels of AMP activate PFKM, indicating a low-energy state in the cell.
- Citrate: High levels of citrate inhibit PFKM, linking glycolysis to the citric acid cycle.
- Fructose-2,6-bisphosphate: This is a potent activator of PFKM, enhancing its affinity for fructose-6-phosphate and reducing its sensitivity to ATP inhibition.
Clinical Significance[edit | edit source]
Mutations in the PFKM gene can lead to a rare genetic disorder known as Glycogen Storage Disease Type VII (also known as Tarui's disease). This condition is characterized by exercise intolerance, muscle cramps, and myoglobinuria due to the inability of muscle cells to effectively utilize glucose for energy.
Research and Applications[edit | edit source]
PFKM is a target for research in metabolic diseases and cancer, as alterations in glycolysis are a hallmark of cancer cell metabolism. Understanding the regulation of PFKM can provide insights into therapeutic strategies for metabolic disorders and cancer.
Also see[edit | edit source]
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Contributors: Prab R. Tumpati, MD