fructose6phosphate

Fructose-6-phosphate, abbreviated F6P, is a phosphorylated sugar phosphate that acts as a central intermediate in carbohydrate metabolism. It is formed from glucose-6-phosphate by the enzyme phosphoglucose isomerase and can be interconverted back to G6P as needed, linking glycolysis and gluconeogenesis.

In glycolysis, F6P represents a key branch point. The enzyme phosphofructokinase-1 converts F6P to fructose-1,6-bisphosphate, a committed step of the pathway that commits carbon toward energy production. Because of its position, F6P flux reflects cellular energy status and substrate availability. F6P also participates in the pentose phosphate pathway; in the non-oxidative phase, it can be rearranged with other sugar phosphates to generate ribose-5-phosphate for nucleotide synthesis and other glycolytic intermediates.

Fructose-6-phosphate is also a precursor in the hexosamine biosynthetic pathway. It is converted to glucosamine-6-phosphate and, through subsequent steps, to UDP-N-acetylglucosamine, a donor for protein glycosylation and other biosynthetic processes. Through these routes, F6P contributes to the production of activated sugars required for cell-surface components and signaling.

Overall, fructose-6-phosphate serves as a pivotal crossroads linking energy production, nucleotide synthesis, and various biosynthetic pathways, allowing cells to balance growth, maintenance, and response to environmental conditions.