Photoaffinity labelling of the rat liver nuclear thyroid hormone receptor with (/sup 125/I)triiodothyronine
(/sup 125/I)Triiodothyronine (T3) was used as a photoreactive probe for the thyroid hormone nuclear receptor in photoaffinity labelling experiments. Autoradiograms of photolysis products electrophoresed on either one or two-dimensional gels showed that (/sup 125/I)T3 covalently, but nonspecifically, labelled many proteins in the partially purified receptor preparations used. However, one of these proteins with an estimated molecular weight of 47,000 and an isoelectric point of approximately 6.2 +/- 0.5 pH units appears to be the thyroid hormone receptor, since, in contrast to the other proteins, its photoinduced labelling was blocked by concentrations of T3 and thyroxine (T4) similar to those that inhibit binding of (/sup 125/I)T3 by the receptor in equilibrium binding assays. In addition, the isoelectric point of the photolabelled protein agrees with that determined in separate equilibrium isoelectric focusing studies. These results indicate that (/sup 125/)T3 can serve as a photoreactive probe for the thyroid hormone nuclear receptor, and they suggest that this receptor is a single polypeptide chain of molecular weight 47,000 with an isoelectric point of 6.2 +/- 0.5 pH units.
- Research Organization:
- Howard Hughes Medical Institute Laboratories, University of California, San Francisco
- OSTI ID:
- 6564629
- Journal Information:
- Endocrinology; (United States), Journal Name: Endocrinology; (United States) Vol. 111:5; ISSN ENDOA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
AFFINITY
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BODY
CELL CONSTITUENTS
CELL NUCLEI
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DECOMPOSITION
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
GLANDS
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LIVER
MAMMALS
NUCLEI
ODD-EVEN NUCLEI
ORGANS
PEPTIDE HORMONES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PHYSIOLOGY
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
THYROID HORMONES
TRACER TECHNIQUES
TRIIODOTHYRONINE
VERTEBRATES