Phosphofructokinase-1 (PFK-1) is one of the most important regulatory
enzymes of
glycolysis. It is an
allosteric enzyme made of 4 subunits and controlled by many
activators and
inhibitors. PFK-1 catalyzes the important "committed" step of
glycolysis, the conversion of
fructose 6-phosphate and
ATP to fructose 1,6-bisphosphate and
ADP. Glycolysis is the foundation for respiration, both anaerobic and aerobic. Because phosphofructokinase (PFK) catalyzes the ATP-dependent phosphorylation to convert fructose-6-phosphate into fructose 1,6-bisphosphate and ADP, it is one of the key regulatory and rate limiting steps of glycolysis. PFK is able to regulate glycolysis through allosteric inhibition, and in this way, the cell can increase or decrease the rate of glycolysis in response to the cell’s energy requirements. For example, a high ratio of ATP to ADP will inhibit PFK and glycolysis. The key difference between the regulation of PFK in eukaryotes and prokaryotes is that in eukaryotes PFK is activated by fructose 2,6-bisphosphate. The purpose of fructose 2,6-bisphosphate is to supersede ATP inhibition, thus allowing eukaryotes to have greater sensitivity to regulation by hormones like glucagon and insulin.