Phosphoglycerate kinase is an enzyme that plays a crucial role in the process of glycolysis, which is the breakdown of glucose to produce energy. It catalyzes the conversion of 3-phosphoglycerate to 1,3-bisphosphoglycerate, using ATP as a phosphate donor. This reaction is essential for energy production in cells. In addition to its role in glycolysis, phosphoglycerate kinase is also involved in gluconeogenesis, the process of synthesizing glucose from non-carbohydrate sources. The enzyme is found in various organisms, including bacteria, plants, and animals, highlighting its importance in cellular metabolism across different life forms.