Structure and function of the Ah receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin. Species difference in molecular properties of the receptors from mouse and rat hepatic cytosols

M. S. Denison, L. M. Vella, A. B. Okey

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Abstract

Molecular properties of cytosolic Ah receptors from livers of Sprague-Dawley rats and C57BL/6N mice were assessed by velocity sedimentation on sucrose gradients and by gel permeation chromatography on Sephacryl S-300. Analyses were done under conditions of both moderate ionic strength (presence of 0.1 M KCl) and high ionic strength (0.4 M KCl). [3H]2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was used as the radioligand. In conditions of moderate ionic strength the receptor from Sprague-Dawley rat liver sedimented at 88 ± 0.05 S, had a Stokes radius of 7.0 ± 0.21 nm, and an apparent relative molecular mass (M(r)) of 257,000 ± 7,700. In conditions of high ionic strength the Ah receptor from rat hepatic cytosol dissociated to a [3H]TCDD-binding subunit which sedimented at 5.6 ± 0.58 S, had a Stokes radius of 5.2 ± 0.24 nm, and an apparent M(r) of 121,000 ± 5,600. The Ah receptor from liver of C57BL/6N mice, in moderate ionic strength conditions, sedimented at 9.4 ± 0.54 S, had a Stokes radius of 7.1 ± 0.12 nm, and an apparent M(r) of 277,000 ± 4,800. Whereas the Ah receptor from rat liver readily dissociated into a [3H]TCDD-binding subunit during brief exposure to 0.4 M KCl, the mouse Ah receptor resisted dissociation. When exposed to 0.4 M KCl for 2 h, the mouse Ah receptor remained at the same molecular size that it had exhibited in moderate ionic strength conditions. Prolonged exposure (16 h) to 0.4 M KCl prior to analysis partially converted the mouse Ah receptor into a smaller [3H]TCDD-binding subunit which sedimented at 4.9 ± 0.07 S, had a Stokes radius of 5.2 ± 0.19 nm, and an apparent M(r) of 105,000 ± 3,800. The potency of seven different Ah receptor agonists in competing with [3H]TCDD for specific receptor sites was slightly different in mouse cytosol than in rat cytosol. By criteria of size, response to high ionic strength environments, and ligand binding preferences the mouse and rat Ah receptors appear to be similar but not identical molecular species.

Original languageEnglish (US)
Pages (from-to)3987-3995
Number of pages9
JournalJournal of Biological Chemistry
Volume261
Issue number9
StatePublished - 1986
Externally publishedYes

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Aryl Hydrocarbon Receptors
Ionic strength
Cytosol
Osmolar Concentration
Rats
Liver
Inbred C57BL Mouse
Sprague Dawley Rats
Gel permeation chromatography
Molecular mass
Sedimentation
Gel Chromatography
Sucrose
Polychlorinated Dibenzodioxins
1,4-dioxin
Ligands

ASJC Scopus subject areas

  • Biochemistry

Cite this

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title = "Structure and function of the Ah receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin. Species difference in molecular properties of the receptors from mouse and rat hepatic cytosols",
abstract = "Molecular properties of cytosolic Ah receptors from livers of Sprague-Dawley rats and C57BL/6N mice were assessed by velocity sedimentation on sucrose gradients and by gel permeation chromatography on Sephacryl S-300. Analyses were done under conditions of both moderate ionic strength (presence of 0.1 M KCl) and high ionic strength (0.4 M KCl). [3H]2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was used as the radioligand. In conditions of moderate ionic strength the receptor from Sprague-Dawley rat liver sedimented at 88 ± 0.05 S, had a Stokes radius of 7.0 ± 0.21 nm, and an apparent relative molecular mass (M(r)) of 257,000 ± 7,700. In conditions of high ionic strength the Ah receptor from rat hepatic cytosol dissociated to a [3H]TCDD-binding subunit which sedimented at 5.6 ± 0.58 S, had a Stokes radius of 5.2 ± 0.24 nm, and an apparent M(r) of 121,000 ± 5,600. The Ah receptor from liver of C57BL/6N mice, in moderate ionic strength conditions, sedimented at 9.4 ± 0.54 S, had a Stokes radius of 7.1 ± 0.12 nm, and an apparent M(r) of 277,000 ± 4,800. Whereas the Ah receptor from rat liver readily dissociated into a [3H]TCDD-binding subunit during brief exposure to 0.4 M KCl, the mouse Ah receptor resisted dissociation. When exposed to 0.4 M KCl for 2 h, the mouse Ah receptor remained at the same molecular size that it had exhibited in moderate ionic strength conditions. Prolonged exposure (16 h) to 0.4 M KCl prior to analysis partially converted the mouse Ah receptor into a smaller [3H]TCDD-binding subunit which sedimented at 4.9 ± 0.07 S, had a Stokes radius of 5.2 ± 0.19 nm, and an apparent M(r) of 105,000 ± 3,800. The potency of seven different Ah receptor agonists in competing with [3H]TCDD for specific receptor sites was slightly different in mouse cytosol than in rat cytosol. By criteria of size, response to high ionic strength environments, and ligand binding preferences the mouse and rat Ah receptors appear to be similar but not identical molecular species.",
author = "Denison, {M. S.} and Vella, {L. M.} and Okey, {A. B.}",
year = "1986",
language = "English (US)",
volume = "261",
pages = "3987--3995",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
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TY - JOUR

T1 - Structure and function of the Ah receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin. Species difference in molecular properties of the receptors from mouse and rat hepatic cytosols

AU - Denison, M. S.

AU - Vella, L. M.

AU - Okey, A. B.

PY - 1986

Y1 - 1986

N2 - Molecular properties of cytosolic Ah receptors from livers of Sprague-Dawley rats and C57BL/6N mice were assessed by velocity sedimentation on sucrose gradients and by gel permeation chromatography on Sephacryl S-300. Analyses were done under conditions of both moderate ionic strength (presence of 0.1 M KCl) and high ionic strength (0.4 M KCl). [3H]2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was used as the radioligand. In conditions of moderate ionic strength the receptor from Sprague-Dawley rat liver sedimented at 88 ± 0.05 S, had a Stokes radius of 7.0 ± 0.21 nm, and an apparent relative molecular mass (M(r)) of 257,000 ± 7,700. In conditions of high ionic strength the Ah receptor from rat hepatic cytosol dissociated to a [3H]TCDD-binding subunit which sedimented at 5.6 ± 0.58 S, had a Stokes radius of 5.2 ± 0.24 nm, and an apparent M(r) of 121,000 ± 5,600. The Ah receptor from liver of C57BL/6N mice, in moderate ionic strength conditions, sedimented at 9.4 ± 0.54 S, had a Stokes radius of 7.1 ± 0.12 nm, and an apparent M(r) of 277,000 ± 4,800. Whereas the Ah receptor from rat liver readily dissociated into a [3H]TCDD-binding subunit during brief exposure to 0.4 M KCl, the mouse Ah receptor resisted dissociation. When exposed to 0.4 M KCl for 2 h, the mouse Ah receptor remained at the same molecular size that it had exhibited in moderate ionic strength conditions. Prolonged exposure (16 h) to 0.4 M KCl prior to analysis partially converted the mouse Ah receptor into a smaller [3H]TCDD-binding subunit which sedimented at 4.9 ± 0.07 S, had a Stokes radius of 5.2 ± 0.19 nm, and an apparent M(r) of 105,000 ± 3,800. The potency of seven different Ah receptor agonists in competing with [3H]TCDD for specific receptor sites was slightly different in mouse cytosol than in rat cytosol. By criteria of size, response to high ionic strength environments, and ligand binding preferences the mouse and rat Ah receptors appear to be similar but not identical molecular species.

AB - Molecular properties of cytosolic Ah receptors from livers of Sprague-Dawley rats and C57BL/6N mice were assessed by velocity sedimentation on sucrose gradients and by gel permeation chromatography on Sephacryl S-300. Analyses were done under conditions of both moderate ionic strength (presence of 0.1 M KCl) and high ionic strength (0.4 M KCl). [3H]2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was used as the radioligand. In conditions of moderate ionic strength the receptor from Sprague-Dawley rat liver sedimented at 88 ± 0.05 S, had a Stokes radius of 7.0 ± 0.21 nm, and an apparent relative molecular mass (M(r)) of 257,000 ± 7,700. In conditions of high ionic strength the Ah receptor from rat hepatic cytosol dissociated to a [3H]TCDD-binding subunit which sedimented at 5.6 ± 0.58 S, had a Stokes radius of 5.2 ± 0.24 nm, and an apparent M(r) of 121,000 ± 5,600. The Ah receptor from liver of C57BL/6N mice, in moderate ionic strength conditions, sedimented at 9.4 ± 0.54 S, had a Stokes radius of 7.1 ± 0.12 nm, and an apparent M(r) of 277,000 ± 4,800. Whereas the Ah receptor from rat liver readily dissociated into a [3H]TCDD-binding subunit during brief exposure to 0.4 M KCl, the mouse Ah receptor resisted dissociation. When exposed to 0.4 M KCl for 2 h, the mouse Ah receptor remained at the same molecular size that it had exhibited in moderate ionic strength conditions. Prolonged exposure (16 h) to 0.4 M KCl prior to analysis partially converted the mouse Ah receptor into a smaller [3H]TCDD-binding subunit which sedimented at 4.9 ± 0.07 S, had a Stokes radius of 5.2 ± 0.19 nm, and an apparent M(r) of 105,000 ± 3,800. The potency of seven different Ah receptor agonists in competing with [3H]TCDD for specific receptor sites was slightly different in mouse cytosol than in rat cytosol. By criteria of size, response to high ionic strength environments, and ligand binding preferences the mouse and rat Ah receptors appear to be similar but not identical molecular species.

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