Pyruvate kinase !

Pyruvate kinase makes the last step of glycolysis and its second ATP; if it fails in red cells, they are destroyed too early.

Updated 2026-10-31

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Key facts

Phosphoenolpyruvate + ADP → pyruvate + ATP, with Mg²⁺ and K⁺; irreversible.
Isoforms: L (liver) and R (red cell) from PKLR; M1 (muscle, brain) and M2 (dividing cells, tumours) from PKM.
Fructose 1,6-bisphosphate activates it ahead of time.

Activator: fructose 1,6-bisphosphate. Inhibitors: ATP and alanine.
In the liver, glucagon phosphorylates it (PKA) and switches it off so that phosphoenolpyruvate goes to gluconeogenesis.

Red-cell pyruvate kinase deficiency (autosomal recessive) causes chronic hemolytic anemia, jaundice, an enlarged spleen and gallstones.
In that deficiency 2,3-BPG builds up: hemoglobin releases oxygen more easily and the anemia is better tolerated.
Mitapivat, a pyruvate kinase activator, is an approved treatment for adults with this deficiency.

Think of the answer, then tap the question to see it.

Which metabolite activates pyruvate kinase ahead of time?

Fructose 1,6-bisphosphate, the product of PFK-1.

Why does pyruvate kinase deficiency cause hemolysis?

Without enough ATP the red cell loses control of its ions and shape, and the spleen removes it.

Which gene encodes red-cell pyruvate kinase?

PKLR (the R and L isoforms).

Educational information, not medical advice. For any symptom, see a health professional.

Sources: PKLR: Pyruvate kinase PKLR (human) (UniProt, 2026); Pyruvate kinase deficiency: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); PKLR gene: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); 2VGB: Human erythrocyte pyruvate kinase (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.