Potent transactivation domains of the Ah receptor and the Ah receptor nuclear translocator map to their carboxyl termini

Sanjay Jain, Kristine M. Dolwick, Jennifer V. Schmidt, Christopher A. Bradfield

Research output: Contribution to journalArticlepeer-review

139 Scopus citations

Abstract

The Ah receptor (AHR) is a ligand-activated transcription factor that is structurally related to its dimerization partner, the Ah receptor nuclear translocator (ARNT), and two Drosophila proteins, SIM and PER. All four proteins contain a region of homology now referred to as a PAS homology domain. In addition, the AHR, ARNT, and SIM harbor a basic region helix- loop-helix motif in their N termini, whereas PER does not. Previous mapping studies of the AHR have demonstrated that the PAS domain contains sequences required for ligand recognition, dimerization, and interaction with the 90- kDa heat shock protein. They also have confirmed that the basic region helix- loop-helix domain plays a role in both dimerization and sequence-specific DNA binding. To identify domains involved in transactivation of target genes, we generated chimeras of AHR/ARNT deletion mutants with the DNA binding region of the yeast Gal4 protein, transiently expressed these in COS-1 cells, and monitored their capacity to activate the chloramphenicol acetyltransferase reporter gene under the control of a minimal promoter driven by enhancer elements recognized by Gal4. Extensive analysis of these fusions revealed that the AHR and ARNT harbor potent transactivation domains within their C termini. Importantly, the amino-terminal halves of both the AHR and ARNT were found to be devoid of transactivation activity.

Original languageEnglish
Pages (from-to)31518-31524
Number of pages7
JournalJournal of Biological Chemistry
Volume269
Issue number50
StatePublished - Dec 16 1994

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