Fig. 2. A) Monomeric unit of PKM2, B) intermolecular interactions between two monomers along the A–^‘A’ axis lead to dimerization of PKM2 and C) two dimers interact at the C–C′ interface which leads to tetramerization of PKM2. D) Tetramer exists in two-states: R-state (active state or tightly bound state) and T-state (inactive state or loosely bound state) of PKM2. In the absence of FBP, PKM2 exists in a mixed population of monomer, dimer, and tetramer that enjoys a T-state conformation (tetramer/inactive). Upon association with FBP, PKM2 changes from the inactive T-state to the active R-state conformation, which favors PEP recognition at the active site and enhances its pyruvate kinase activity.