Everything about Phosphofructokinase 1 totally explained
Phosphofructokinase-1 (PFK-1) is the most important regulatory
enzyme of
glycolysis. It is an
allosteric enzyme made of 4 subunits and controlled by several
activators and
inhibitors. PFK-1 catalyzes one of the important "committed" steps of
glycolysis, the conversion of
fructose 6-phosphate and
ATP to fructose 1,6-bisphosphate and
ADP.
This step is subject to extensive regulation since it isn't only irreversible, but also because the original substrate is forced to proceed down the glycolytic pathway after this step. This leads to a precise control of glucose and the other
monosaccharides
galactose and
fructose going down the glycolysis pathway. Before this enzyme's reaction,
glucose-6-phosphate can potentially travel down the
pentose phosphate pathway, or be converted to glucose-1-phosphate and polymerized into the storage form Glycogen.
Regulation
PFK1 is
allosterically inhibited by ATP and citrate (from the
citric acid cycle) and its product. It is also inhibited by low pH to prevent the accumulation of hydrogen ions in muscle. The enzyme has two sites with different affinities for ATP which is both a
substrate and an inhibitor.
PFK1 is
allosterically activated by a high concentration of
AMP, but the most potent activator is
fructose 2,6-bisphosphate, which is also produced from fructose-6-phosphate by
PFK2.
PFK is inhibited by
glucagon through repression of synthesis.
The precise regulation of PFK 1 prevents
glycolysis and
gluconeogenesis from occurring simultaneously.
Genes
There are three phosphofructokinase genes in humans:
Further Information
Get more info on 'Phosphofructokinase 1'.
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