Chemically induced dimerization is the controlled dimerization of a pair of proteins, through any one of a number of classes of dimerizers. The dimerizer acts to bring the two proteins together, and the induced dimerization can be used to increase the effective molarity of a protein at a certain cellular substructure, thus causing chemically induced proximity (CIP) of the two dispersed proteins. The result of dimerization is flexible, as it is directed by the domain fused to the protein, which is being used to effect the dimerization. The combination of a DNA binding domain (DBD) and a protein binding domain, the activation domain (AD), within one species has led to the creation of molecules which can be used to cause the dimerization of DNA and protein complexes. The alternative proteins (and corresponding ligands) to induce dimerization have been developed, including dihydrofolate reductase (DHFR) and a methotrexate (MTX) based ligand. The natural product coumermycin cause dimerization of a bacterial DNA gyrase B subunit (GyrB) and has been used as a dimerizer.