What is the main substrate that PFK-1 phosphorylates in glycolysis?

PFK-1, or phosphofructokinase-1, is a key regulatory enzyme in glycolysis that catalyzes the phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate. In this reaction, PFK-1 transfers a phosphate group from ATP to fructose 6-phosphate, which effectively converts it into fructose 1,6-bisphosphate, a crucial intermediate in the glycolytic pathway. This step is significant as it serves as a major regulatory point for the entire glycolytic process, controlling the rate at which glucose is broken down for energy.

Understanding the role of PFK-1 in glycolysis highlights its importance in cellular metabolism, as it helps manage the flow of carbon through the pathway based on the energy needs of the cell. The phosphorylation of fructose 6-phosphate maintains the unidirectional flow of glucose metabolism, primarily since the product fructose 1,6-bisphosphate is committed to further along in glycolysis.