Pyruvate kinase is an important enzyme in the process of glycolysis, which is how cells convert glucose into energy. It catalyzes the final step of glycolysis, converting phosphoenolpyruvate (PEP) into pyruvate while producing adenosine triphosphate (ATP), the energy currency of the cell. This reaction is crucial for energy production in both aerobic and anaerobic conditions. The activity of pyruvate kinase is regulated by various factors, including fructose-1,6-bisphosphate, which activates it, and ATP, which inhibits it. This regulation helps the cell maintain energy balance and respond to changing energy demands.