Pyruvate Kinase is an important enzyme in the process of glycolysis, which is how cells break down glucose to produce energy. It catalyzes the conversion of phosphoenolpyruvate (PEP) to pyruvate, generating ATP, the energy currency of the cell. This reaction is a key regulatory step in the glycolytic pathway. The activity of Pyruvate Kinase is influenced by various factors, including the availability of fructose-1,6-bisphosphate and the energy status of the cell. It exists in different forms, or isoenzymes, in various tissues, such as the liver and muscle, allowing for specialized regulation based on the cell's needs.