Recent studies indicate that the potency and agonist or antagonist activity of steroid hormone ligands are dependent, in part, on ligand–receptor binding affinity as well as the conformation of the ligand–receptor complex. The binding of ligands to hormone receptors is thought to involve interactions by which shapes of both the receptor and ligand are modified in the formation of the ligand–rec...

Organohalogen compounds, the pesticides aldrin, dieldrin, endrin, hexachlorobenzene, mirex, Sigmachlordanes, SigmaDDTs, Sigmaheptachlors, Sigmatoxaphenes, and the industrial chemicals SigmaPCBs and SigmaPBDEs, as well as total dioxin-like equivalents (TEQH4IIE-luc), were measured in eggs of two Ardeid species, the little egret (Egretta garzetta) and black-crowned night heron (Nycticorax nyctico...

Changes in the concentration or subcellular location of the key proteins involved in signal transduction pathways have been shown to impact gene regulation. Studies were designed to evaluate the relationship between aryl hydrocarbon receptor (AHR) localization, stability, and gene regulation in a defined system where the endogenous AHR protein could be evaluated. The findings indicate that trea...

Aryl hydrocarbon receptor (AhR) is a transcription factor that works as a dioxin receptor and is also involved in various physiological phenomena, including development and cell proliferation. Here, we show that the Galpha13 signal destabilizes AhR by promoting the ubiquitination of AhR. Galpha13 interacts directly with AhR-interacting protein (AIP) and inhibits the interaction between AhR and ...

BACKGROUND Aryl hydrocarbon receptor (AhR) ligands adversely affect many biological processes. However, assessment of the significance of human exposures is hampered by an incomplete understanding of how complex mixtures affect AhR activation/inactivation. OBJECTIVES These studies used biological readouts to provide a broader context for estimating human risk than that obtained with serum ext...

BACKGROUND Cytochrome P450 1 (CYP1) genes are biomarkers for aryl hydrocarbon receptor (AHR) agonists and may be involved in some of their toxic effects. CYP1s other than the CYP1As are poorly studied in birds. Here we characterize avian CYP1B and CYP1C genes and the expression of the identified CYP1 genes and AHR1, comparing basal and induced levels in chicken and quail embryos. METHODOLOGY/...

The cytosolic transcription factor known as the aryl hydrocarbon receptor (AhR) undergoes transformation to a DNA-binding form by a series of processes initiated by binding of ligand. Subsequent steps include dissociation of several proteins that are complexed with the inactive receptor, nuclear translocation, and dimerization with Arnt. We have used limited proteolysis of the in vitro-translat...

The aryl hydrocarbon receptor nuclear translocator (ARNT) is a basic helix-loop-helix transcription factor that forms heterodimers with the aryl hydrocarbon receptor (AhR) or hypoxia inducible factor-1alpha to activate transcription via xenobiotic response element or hypoxia response element, respectively. Thus, it plays a major role in two key biochemical pathways involved in tumor growth. We ...