DNA Binding of the Transformed Guinea Pig Hepatic Ah Receptor Complex: Identification and Partial Characterization of 2 High-Affinity DNA-Binding Forms

The AH Receptor of the Most Dioxin-Sensitive Species, Guinea Pig, Is Highly Homologous to the Human AH Receptor

“…In the present study, Western blot clearly showed a size difference between Guinea pig and hamster. The size of 103 (33) or 105 kDa (34) for the Guinea pig AHR has been reported earlier and is in accordance with our findings. Interestingly, the calculated molecular mass is 95 kDa, somewhat smaller than the electrophoretically obtained size.…”

“…Comparison between the LD50 Values for TCDD (14,40,41,16), the Number of Glutamine Residues in the Q-Rich Subdomain of AHR, and the Overall Homology to Guinea Pig AHR (34,42,35,18) sites for dioxin sensitivity and that AHR structure does not provide any obvious support for the assumed general dioxin resistance of humans.…”

Activation of the Ah Receptor by Tryptophan and Tryptophan Metabolites

“…Gel Retardation Analysis. DNA binding analysis of cytosolic AhR complexes transformed in vitro was carried out as we have described in detail (41,42). Briefly, guinea pig cytosol (16 mg of protein/mL) was incubated with TCDD (20 nM), TRP or a TRP metabolite at the indicated concentration, or carrier solvent [DMSO, water, or ethanol (20 µL/mL)] for 2 h at 20 °C, followed by gel retardation analysis.…”

Identification and Functional Characterization of Two Highly Divergent Aryl Hydrocarbon Receptors (AHR1 and AHR2) in the TeleostFundulus heteroclitus

“…Data from AHR-null mice indicating that this AHR gene is necessary for CYP1A induction and TCDD toxicity (10,11,86) do not preclude the existence of a second AHR that could be involved in other aspects of dioxin signaling or in modulating AHR1 function. There is biochemical evidence for multiple forms of the AHR in mammals (87)(88)(89)(90); these may or may not represent products of multiple AHR genes. Thus, the presence of a second AHR in mammals remains uncertain.…”