The role of chaperone proteins in the aryl hydrocarbon receptor core complex

Chem Biol Interact. 2002 Sep 20;141(1-2):25-40. doi: 10.1016/s0009-2797(02)00064-9.


The aryl hydrocarbon receptor (AhR) exists in the absence of a ligand as a tetrameric complex composed of a 95-105 kDa ligand binding subunit, a dimer of hsp90, and the immunophilin-like X-associated protein 2 (XAP2). XAP2 has a highly conserved carboxy terminal tetratricopeptide repeat domain that is required for both hsp90 and AhR binding. Hsp 90 appears to be involved in the initial folding of newly synthesized AhR, stabilization of ligand binding conformation of the receptor, and inhibition of constitutive dimerization with ARNT. XAP2 is capable of stabilizing the AhR, as well as enhancing cytoplasmic localization of the receptor. XAP2 binds to both the AhR and hsp90 in the receptor complex, and is capable of independently binding to both hsp90 and the AhR. However, the exact functional role for XAP2 in the AhR complex remains to be fully established.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Intracellular Signaling Peptides and Proteins
  • Ligands
  • Macromolecular Substances
  • Molecular Sequence Data
  • Protein Binding
  • Protein Subunits
  • Proteins / metabolism*
  • Receptors, Aryl Hydrocarbon / chemistry*
  • Receptors, Aryl Hydrocarbon / metabolism*


  • Intracellular Signaling Peptides and Proteins
  • Ligands
  • Macromolecular Substances
  • Protein Subunits
  • Proteins
  • Receptors, Aryl Hydrocarbon
  • aryl hydrocarbon receptor-interacting protein