Chemical cross-linking of the cytosolic and nuclear forms of the Ah receptor in hepatoma cell line 1c1c7

Biochem Biophys Res Commun. 1992 Jan 15;182(1):55-62. doi: 10.1016/s0006-291x(05)80111-1.


Both cytosolic and high salt nuclear extracts were isolated from Hepa 1c1c7 cells incubated with 2-azido-3[125I]iodo-7,8-dibromo-dibenzo-p-dioxin ([125I]N3Br2DpD). The [125I]N3Br2DpD-labeled cytosolic fraction was subjected to chemical cross-linking with dimethyl pimelimidate and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Chemical cross-linking of the cytosolic form of the AhR revealed monomeric (97 kDa), dimeric (185 kDa), trimeric (281 kDa), and tetrameric (327 kDa) complexes. In a time course of exposure to the cross-linking reagent, the largest form given above became the predominant AhR form observed in the cytosolic extracts. The 327 kDa cytosolic species apparently consists of a 97 kDa AhR, an approximately 88 kDa protein, an approximately 96 kDa protein, and an approximately 46 kDa protein. Nuclear extracts from [125I]N3Br2DpD-labeled Hepa 1c1c7 cells were applied to sucrose density gradients. The 6 S nuclear receptor peak fractions were pooled and subjected to chemical cross-linking. Analysis by SDS-PAGE revealed a monomeric (97 kDa) ligand binding protein and a dimeric (182 kDa) complex. This would suggest that the nuclear 6 S AhR consists of a 97 kDa AhR and an approximately 85 kDa protein. These findings would indicate that the AhR exists in cytosol as a tetrameric species, while in the nucleus the AhR exists as a heterodimer.

Publication types

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

MeSH terms

  • Carcinoma, Hepatocellular
  • Cell Fractionation
  • Cell Line
  • Cell Nucleus / metabolism*
  • Centrifugation, Density Gradient
  • Cross-Linking Reagents
  • Cytosol / metabolism
  • Electrophoresis, Polyacrylamide Gel
  • Liver Neoplasms
  • Macromolecular Substances
  • Molecular Weight
  • Polychlorinated Dibenzodioxins / metabolism
  • Polyenes / pharmacology
  • Receptors, Aryl Hydrocarbon
  • Receptors, Drug / isolation & purification
  • Receptors, Drug / metabolism*


  • Cross-Linking Reagents
  • Macromolecular Substances
  • Polychlorinated Dibenzodioxins
  • Polyenes
  • Receptors, Aryl Hydrocarbon
  • Receptors, Drug
  • hamycin