Phosphoenolpyruvate (PEP) is a key intermediate in the process of cellular metabolism, particularly in glycolysis, where it plays a crucial role in the conversion of glucose into energy. PEP is formed from 2-phosphoglycerate and is known for its high-energy phosphate bond, which is used to generate adenosine triphosphate (ATP) during the final steps of glycolysis. In addition to its role in glycolysis, PEP is also involved in gluconeogenesis, the process of synthesizing glucose from non-carbohydrate sources. It serves as a substrate for the enzyme pyruvate kinase, which catalyzes the conversion of PEP to pyruvate, releasing energy that is essential for various cellular functions.