The enzyme-catalysed transfer of a phosphoryl group from ATP is an important reaction in a wide variety of biological processes.

The identical tetramer subunits adopt 2 different conformations: in a 'closed' state, the bound magnesium ion bridges the phosphoryl groups of the enzyme products (ADP and fructose-1,6-bisphosphate); and in an 'open' state, the magnesium ion binds only the ADP,[6] as the 2 products are now further apart.

These conformations are thought to be successive stages of a reaction pathway that requires subunit closure to bring the 2 molecules sufficiently close to react.

[11][7][10] PFK is found in isoform versions in skeletal muscle (PFKM), in the liver (PFKL), and from platelets (PFKP), allowing for tissue-specific expression and function.

[12][13] Deficiency in PFK leads to glycogenosis type VII (Tarui's disease), an autosomal recessive disorder characterised by severe nausea, vomiting, muscle cramps and myoglobinuria in response to bursts of intense or vigorous exercise.