AhR

The aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor that controls the expression of a diverse set of genes. In the absence of ligand, AHR is retained in the cytoplasm. Upon ligand binding AHR translocates to the nucleus where it forms a heterodimer with aryl hydrocarbon receptor nuclear translocator (ARNT) (1). This receptor complex then recognizes AHR-response elements in target genes to regulate their transcription.

AH receptor-interacting protein (AIP) is a 37 kD immunophilin-like factor found in a variety of tissues with expression levels ranging from high (spleen, thymus, pituitary heart, placenta and skeletal muscle) to low (liver, kidney and lung). It mediates aryl hydrocarbon receptor (AhR) signaling either through ligand receptivity and/or modulating nuclear targeting and has been shown to bind to both the AhR itself as well as the AhR nuclear translocator (ARNT).