Phosphofructokinase (PFK) is an important enzyme in the process of glycolysis, which is how cells break down glucose to produce energy. PFK helps convert fructose-6-phosphate into fructose-1,6-bisphosphate, a key step that regulates the flow of glucose through the glycolytic pathway. This reaction requires energy in the form of ATP, making PFK a crucial control point in energy metabolism. PFK is sensitive to various molecules that signal the energy status of the cell. For example, high levels of ATP indicate sufficient energy, which can inhibit PFK activity, while increased levels of AMP signal low energy and stimulate its activity. This regulation helps maintain balance in cellular energy production.