May catalyze the interconversion of 2-phosphoglycerate and 3- phosphoglycerate, a crucial step in glycolysis, by using 2,3- bisphosphoglycerate. May also catalyze the interconversion of (2R)-2,3- bisphosphoglycerate and (2R)-3-phospho-glyceroyl phosphate. . This is the function of PGAM4 (phosphoglycerate mutase family member 4, ENSG00000226784).