Oxaloacetate is a four-carbon molecule that plays a crucial role in the metabolic pathway known as the Krebs cycle, or citric acid cycle. It is formed from the combination of acetyl-CoA and oxaloacetate itself, and it helps in the production of energy by facilitating the conversion of carbohydrates, fats, and proteins into usable energy. In addition to its role in energy production, oxaloacetate is involved in gluconeogenesis, the process of generating glucose from non-carbohydrate sources. It can also serve as a precursor for the synthesis of certain amino acids, making it important for overall metabolic balance and cellular function.