Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that plays a role as an intracellular mediator of the xenobiotic signaling pathway. AhR is a nucleo-cytoplasmic shuttling protein mediated by nuclear localization signals (NLS) and nuclear export signals (NES). Protein kinase C-mediated phosphorylation of NLS inhibits the ligand-dependent nuclear import of AhR, suggesting a two-step mechanism of nuclear import. Cell density regulates AhR intracellular localization, due to modulation of nuclear export activity. The p38 mitogen-activated protein kinase (MAPK)-mediated phosphorylation of NES and its dephosphorylation, regulated by cell-cell contact signals, may have pivotal roles in the novel AhR relocalization.
