AhR's transactivation domain communicates the induction signal from enhancer to promoter probably via protein-protein interactions, thereby facilitating the binding of general transcription factors to the promoter.
Arnt can also interact with other bHLH/PAS proteins, thereby mediating responses to additional environmental stimuli. In particular, Arnt heterodimerizes with hypoxia-inducible factor 1 alpha (HIF1 alpha) in response to low oxygen tension, and the HIF1 alpha/Arnt heterodimer alters the transcription of hypoxia-responsive genes.