Catalyzes the interconversion of 2-phosphoglycerate and 3-phosphoglycerate. (2R)-2-phosphoglycerate = (2R)-3-phosphoglycerate Binds 2 manganese or magnesium ions per subunit (By similarity). Cobalt and nickel are less efficient (PubMed:17897734). Activity is not affected by 2,3-bisphosphoglycerate. Optimum pH is 7.5-8.5. Optimum temperature is 32 degrees Celsius. Active between 17 and 32 degrees Celsius. Carbohydrate degradation; glycolysis; pyruvate from D-glyceraldehyde 3-phosphate: step 3/5. Belongs to the BPG-independent phosphoglycerate mutase family.