Characterization of multiple forms of the Ah receptor: Recognition of a dioxin-responsive enhancer involves heteromer formation

Journal Article · Tue Mar 19 04:00:00 EST 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00225a026· OSTI ID:5026321

Gasiewicz, T A; Henry, E C ^[1]; Elferink, C J ^[2]

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1. Univ. of Rochester School of Medicine, New York (United States)
2. Stanford Univ. School of Medicine, CA (United States)

The authors have employed a combination of gel retardation, protein-DNA cross-linking, and protein-protein cross-linking techniques to further examine the 2,3,7,8-tetracholorodibenzo-p-dioxin- (TCDD-) dependent changes in the Ah receptor that result in a DNA-binding conformation. Gel retardation analysis of DNA-Sepharose chromatographic fractions of rat hepatic cytosol indicated that TCDD-dependent and sequence-specific DNA binding coeluted with a 200-kDa form of the Ah receptor (peak 2) previoulsly characterized as being multimeric and having high affinity for calf thymus DNA. The TCDD-cound, 100-kDa form of the receptor (peak 1) bound weakly to the DNA recognition motif. These results indicated that the DNA-binding form of the Ah receptor is a multimer. SDS-polyacrylamide gel electrophoresis of peak 2 cross-linked to a bromodeoxyuridine-substituted DNA recognition motif indicated that this form of the receptor present in rat hepatic cytosol is composed of at least two DNA-bginding proteins of approximately 100 and 110 kDa. Using the chemical cross-linking agent dimethyl pimelimidate, they further established that the 100-kDa form of the receptor (peak 1) associates with a different protein to generate the receptor form (peak 2) that binds to the dioxin-responsive enhancer. Photoaffinity-labeling studies indicated that only the 100-kDa protein (peak 1), and not the 110-kDa protein, binds ligand. Together, these observations imply that the DNA-binding form of the Ah receptor exists as a heteromer.

• OSTI ID: 5026321
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 30:11; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMICAL REACTIONS
CROSS-LINKING
DAYS LIVING RADIOISOTOPES
DIOXIN
ELECTRON CAPTURE RADIOISOTOPES
ELECTROPHORESIS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODINE 125
IODINE ISOTOPES
ISOTOPES
LIGHT NUCLEI
MEMBRANE PROTEINS
MOLECULAR STRUCTURE
NUCLEI
NUCLEIC ACIDS
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OLIGONUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
POLYMERIZATION
PROTEINS
RADIOISOTOPES
RECEPTORS
TRITIUM COMPOUNDS