The enzyme from the bacterium Escherichia coli is bifunctional and catalyses both the phosphorylation and dephosphorylation of EC
2.7.9.2, pyruvate, water dikinase. cf. EC
2.7.4.28, ([pyruvate, water dikinase] phosphate) phosphotransferase [1]. The enzyme is specific for a reaction intermediate form of EC
2.7.9.2, where it phosphorylates an active site histidine [1]. It has no activity toward EC
2.7.9.1 pyruvate, phosphate dikinase (cf. EC
2.7.11.32, [pyruvate, phosphate dikinase] kinase).