Where is PFK2 found?
liver
The enzyme is important in the regulation of hepatic carbohydrate metabolism and is found in greatest quantities in the liver, kidney and heart.
What is the function of PFK2?
PFK2 is a bi-functional enzyme that functions as a kinase for the conversion of F-6-P to F-2,6-bisP in its dephosphorylated state and as a phosphatase for the conversion of F-2,6-bisP back to F-6-P in its phosphorylated state.
What happens when PFK2 is phosphorylated?
When PFK-2/F-2,6-bisphosphatase is phosphorylated (P*) by Protein kinase A in muscle, PFK-2 is activated and F-2,6-bisphosphatase is inhibited. The concentration of Fructose-2,6-bisphosphate is raised so glycolysis is activated. P and P* are two different sites on the PFK-2/F-2,6-bisphosphatase enzyme complex.
What is the role of fructose 2,6-bisphosphate?
Fructose-2,6-bisphosphate functions as a potent allosteric activator of PFK1, a rate-limiting enzyme of glycolysis. Therefore, TIGAR inhibits glycolysis, thereby redirecting cellular glucose metabolism to the pentose phosphate pathway shunt.
What is the function of PFK2 in glycolysis?
PFK2 catalyzes formation or degradation of the regulator of glycolysis fructose 2,6-bisphosphate (fructose 2,6-P2), depending on its phosphorylation state (ser-32), and is also a glucokinase-binding protein.
What is bifunctional enzyme?
Bifunctional enzymes generally contain two large structural domains whose association facilitates metabolic pathway control and/or allows more efficient substrate conversion. Bifunctional enzymes are sometimes co-expressed with monofunctional forms.
What are effect does glucagon have on PFK2?
Glucagon caused phosphorylation of PFK2-ser-32, lowered the fructose 2,6-P2 concentration, and inhibited glucose-induced translocation of glucokinase.
What are bifunctional enzymes?
Why does muscle not have glucose 6 phosphatase?
1 Glucose 6-Phosphatase. Thus, glucose 6-phosphate generated from glycogenolysis and glucogenesis is released from the liver into the circulation for peripheral use. There does not appear to be glucose 6-phosphatase in skeletal muscle; hence, muscle glycogen is not a source of circulating glucose.
How does fructose2 6 BP control glycolysis and gluconeogenesis?
Glucose increases the concentration of fructose-2,6-bisphosphate in vivo, probably by increasing the availability of fructose-6-phosphate, thereby stimulating PFK-2, the kinase for which this is a substrate and inhibiting the phosphatase, FBPase-2. The effect is to increase glycolysis and inhibit gluconeogenesis.
What activates FBPase?
As an example of this type of regulation of gluconeogenesis, acetyl CoA allosterically activates PC, while FBPase is activated by ATP and inhibited by AMP and fructose-2,6-bisphosphate.
Where is the pfkb2 gene located on the chromosome?
High concentrations of F-6-P will activate kinase function and increase rates of glycolysis, whereas low concentrations of F-6-P will stabilize phosphatase action. The PFKB2 gene is located on chromosome 1.
Where is the spleen located in the human body?
The spleen is an organ in the upper far left part of the abdomen, to the left of the stomach. The spleen varies in size and shape between people, but it’s commonly fist-shaped, purple, and about 4 inches long. The spleen also helps fight certain kinds of bacteria that cause pneumonia and meningitis.
How does insulin activate the liver PFK-2 complex?
Insulin activates liver PFK-2 function to indicate a high abundance of blood glucose is available for glycolysis. Insulin activates a protein phosphatase which dephosphorylates the PFK-2 complex and causes favored PFK-2 activity. PFK-2 then increases production of F-2,6-P 2.
How is PFK-2 regulated in skeletal muscle and fetal tissue?
In contrast to most other PFK-2 tissues, PFK-2 in both skeletal muscle and fetal tissue is solely regulated by concentrations of Fructose-6-phosphate. Within their first exon, there are no regulatory sites that require phosphorylation/dephosphorylation to provoke a change in function.