Oxaloacetate is a four-carbon molecule that plays a crucial role in the metabolic pathways of living organisms. It is an intermediate in the Krebs cycle, also known as the citric acid cycle, which is essential for energy production in cells. This cycle helps convert carbohydrates, fats, and proteins into usable energy in the form of ATP. In addition to its role in energy metabolism, oxaloacetate is involved in gluconeogenesis, the process of producing glucose from non-carbohydrate sources. It can also participate in amino acid synthesis, making it important for overall metabolic balance and the production of essential biomolecules in the body.