AraC acts as an activator in the presence of arabinose. AraC undergoes a conformational change when arabinose binds to the dimerization domain of AraC. As a result, the AraC-arabinose complex falls off from "araO2" and breaks the DNA loop. Hence, it is more energetically favourable for AraC-arabinose to bind to two adjacent DNA half sites: "araI1" and "araI2" in the presence of arabinose. One of the monomers binds "araI1", the remaining monomer binds "araI2" - in other words, binding of AraC to "araI2" is allosterically induced by arabinose. One of the AraC monomers places near to the "araBAD" promoter in this configuration, which helps to recruit RNA polymerase to the promoter to initiate transcription.