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Phosphorylation of a specific residue may prompt a shift that stabilizes either kinase or phosphatase domain function. This regulation signal thus controls whether F-2,6-P 2 will be synthesized or degraded. [19] Furthermore, the allosteric regulation of PFK2 is very similar to the regulation of PFK1. [20]
PFK exists as a homotetramer in bacteria and mammals (where each monomer possesses 2 similar domains) and as an octomer in yeast (where there are 4 alpha- (PFK1) and 4 beta-chains (PFK2), the latter, like the mammalian monomers, possessing 2 similar domains [3]). This protein may use the morpheein model of allosteric regulation. [5]
Xylulose-5-phosphate also plays a crucial role in the regulation of glycolysis through its interaction with the bifunctional enzyme PFK2/FBPase2. Specifically, it activates protein phosphatase, which then dephosphorylates PFK2/FBPase2. This inactivates the FBPase2 activity of the bifunctional enzyme and activates its PFK2 activity. [2]
Fru-2,6-P 2 strongly activates glucose breakdown in glycolysis through allosteric modulation (activation) of phosphofructokinase 1 (PFK-1).Elevated expression of Fru-2,6-P 2 levels in the liver allosterically activates phosphofructokinase 1 by increasing the enzyme’s affinity for fructose 6-phosphate, while decreasing its affinity for inhibitory ATP and citrate.
The PFKFB3 gene is mapped to single locus on chromosome 10 (10p15-p14). [5] [6] It spans a region of 32.5kb with an open reading frame that is 5,675bp long.It is estimated to consist of 19 exons, of which 15 are regularly expressed. [8]
Loss of PTEN function leads to over-activation of Akt and is common in cancer cells (PTEN is a tumour suppressor). SH2-containing Inositol Phosphatase (SHIP) also dephosphorylates PI(3,4,5)P 3, at the 5' position of the inositol ring. [22] The PI3K-Akt pathway regulates PTEN levels by affecting its transcription and activity.
The PFKP gene encodes the platelet isoform of phosphofructokinase (PFK) (ATP:D-fructose-6-phosphate-1-phosphotransferase, EC 2.7.1.11). PFK catalyzes the irreversible conversion of fructose 6-phosphate to fructose 1,6-bisphosphate and is a key regulatory enzyme in glycolysis.
This protein regulates fructose-2,6-bisphosphate levels in the heart, while a related enzyme encoded by a different gene regulates fructose-2,6-bisphosphate levels in the liver and muscle. This enzyme functions as a homodimer. Two transcript variants encoding two different isoforms have been found for this gene. [5]