The tetrameric form is the pyruvate kinase structure in its R-state conformation, namely with high binding affinity to PEP. In contrast, the dimeric form is its structure in T-state conformation, namely with a low binding affinity to PEP. As a result, gene expression can be regulated by converting the highly active tetrameric form of PKM2, which yields high PEP concentrations, into an inactive dimeric form, which yields a PEP concentration of nearly zero.[3]