Identification of thyroid hormone receptors in rat liver nuclei by photoaffinity labeling with L-thyroxine and triiodo-L-thyronine

Beatrice Dozin, Hans J. Cahnmann, Vera M. Nikodem

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Photoaffinity labeling of rat liver nuclear extract with underivatized thyroid hormones was performed after incubation with 1 nM [3′,5′-125I]thyroxine ([125I]T4) or [3′-125I]triiodothyronine ([125I]T3) by irradiation with light above 300 nm. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the covalently photolabeled nuclear extract revealed four distinct hormone binding proteins of molecular masses 96, 56, 45, and 35 kilodaltons (kDa), respectively. Distribution of the hormone among these proteins was similar for T4 and T3. The 56- and 45-kDa proteins were the most prominently labeled. The specificity of the photoattachment of thyroid hormones to these nuclear proteins was verified by the irradiation of eight randomly chosen proteins and two proteins known to have thyroid hormone binding sites, human thyroxine binding globulin and bovine serum albumin. Only the latter two were photolabeled with [125I]T4. Competition studies performed by incubating nuclear extracts with [125I]T4 or [125I]T3 in the presence of increasing amounts of the corresponding unlabeled hormone (10-, 100-, and 1000-fold molar excess) demonstrated that (1) photoattachment of labeled T3 or T4 to the 56- and 45-kDa proteins was inhibited by 67-78% and 73-85%, respectively, after incubation with a 1000-fold molar excess of unlabeled hormone, (2) in the presence of lower molar excesses of the corresponding competitor (10- and 100-fold), photoattachment of labeled T3 or T4 to the 56- and 45-kDa receptors was gradually inhibited to a similar extent on both proteins, and (3) the 35- and 96-kDa proteins, although having thyroid hormone binding sites, display lower binding activities since the inhibition of photoattachment of labeled T3 or T4 by a 1000-fold molar excess of unlabeled hormone did not exceed 30-42% and 26-49%, respectively. Hence, only the 56- and 45-kDa proteins are thyroid hormone receptors. The similar behavior of the 56- and 45-kDa receptors in the competition studies suggests a structural relationship between the two proteins. Digestion of the 56- and 45-kDa proteins with Staphylococcus aureus V8 protease yielded virtually identical peptide patterns, indicating that both receptor proteins share homologous amino acid sequences.

Original languageEnglish
Pages (from-to)5197-5202
Number of pages6
JournalBiochemistry
Volume24
Issue number19
Publication statusPublished - 1985

Fingerprint

Thyronines
Thyroid Hormone Receptors
Thyroxine
Liver
Labeling
Rats
Proteins
Thyroid Hormones
Hormones
Binding Sites
Irradiation
Amino Acid Sequence Homology
Liver Extracts
Molecular mass
Triiodothyronine
Bovine Serum Albumin
Nuclear Proteins
Electrophoresis
Sodium Dodecyl Sulfate
Staphylococcus aureus

ASJC Scopus subject areas

  • Biochemistry

Cite this

Identification of thyroid hormone receptors in rat liver nuclei by photoaffinity labeling with L-thyroxine and triiodo-L-thyronine. / Dozin, Beatrice; Cahnmann, Hans J.; Nikodem, Vera M.

In: Biochemistry, Vol. 24, No. 19, 1985, p. 5197-5202.

Research output: Contribution to journalArticle

@article{aff9ae31e2cd42dd85dac039c0f4acf0,
title = "Identification of thyroid hormone receptors in rat liver nuclei by photoaffinity labeling with L-thyroxine and triiodo-L-thyronine",
abstract = "Photoaffinity labeling of rat liver nuclear extract with underivatized thyroid hormones was performed after incubation with 1 nM [3′,5′-125I]thyroxine ([125I]T4) or [3′-125I]triiodothyronine ([125I]T3) by irradiation with light above 300 nm. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the covalently photolabeled nuclear extract revealed four distinct hormone binding proteins of molecular masses 96, 56, 45, and 35 kilodaltons (kDa), respectively. Distribution of the hormone among these proteins was similar for T4 and T3. The 56- and 45-kDa proteins were the most prominently labeled. The specificity of the photoattachment of thyroid hormones to these nuclear proteins was verified by the irradiation of eight randomly chosen proteins and two proteins known to have thyroid hormone binding sites, human thyroxine binding globulin and bovine serum albumin. Only the latter two were photolabeled with [125I]T4. Competition studies performed by incubating nuclear extracts with [125I]T4 or [125I]T3 in the presence of increasing amounts of the corresponding unlabeled hormone (10-, 100-, and 1000-fold molar excess) demonstrated that (1) photoattachment of labeled T3 or T4 to the 56- and 45-kDa proteins was inhibited by 67-78{\%} and 73-85{\%}, respectively, after incubation with a 1000-fold molar excess of unlabeled hormone, (2) in the presence of lower molar excesses of the corresponding competitor (10- and 100-fold), photoattachment of labeled T3 or T4 to the 56- and 45-kDa receptors was gradually inhibited to a similar extent on both proteins, and (3) the 35- and 96-kDa proteins, although having thyroid hormone binding sites, display lower binding activities since the inhibition of photoattachment of labeled T3 or T4 by a 1000-fold molar excess of unlabeled hormone did not exceed 30-42{\%} and 26-49{\%}, respectively. Hence, only the 56- and 45-kDa proteins are thyroid hormone receptors. The similar behavior of the 56- and 45-kDa receptors in the competition studies suggests a structural relationship between the two proteins. Digestion of the 56- and 45-kDa proteins with Staphylococcus aureus V8 protease yielded virtually identical peptide patterns, indicating that both receptor proteins share homologous amino acid sequences.",
author = "Beatrice Dozin and Cahnmann, {Hans J.} and Nikodem, {Vera M.}",
year = "1985",
language = "English",
volume = "24",
pages = "5197--5202",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "19",

}

TY - JOUR

T1 - Identification of thyroid hormone receptors in rat liver nuclei by photoaffinity labeling with L-thyroxine and triiodo-L-thyronine

AU - Dozin, Beatrice

AU - Cahnmann, Hans J.

AU - Nikodem, Vera M.

PY - 1985

Y1 - 1985

N2 - Photoaffinity labeling of rat liver nuclear extract with underivatized thyroid hormones was performed after incubation with 1 nM [3′,5′-125I]thyroxine ([125I]T4) or [3′-125I]triiodothyronine ([125I]T3) by irradiation with light above 300 nm. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the covalently photolabeled nuclear extract revealed four distinct hormone binding proteins of molecular masses 96, 56, 45, and 35 kilodaltons (kDa), respectively. Distribution of the hormone among these proteins was similar for T4 and T3. The 56- and 45-kDa proteins were the most prominently labeled. The specificity of the photoattachment of thyroid hormones to these nuclear proteins was verified by the irradiation of eight randomly chosen proteins and two proteins known to have thyroid hormone binding sites, human thyroxine binding globulin and bovine serum albumin. Only the latter two were photolabeled with [125I]T4. Competition studies performed by incubating nuclear extracts with [125I]T4 or [125I]T3 in the presence of increasing amounts of the corresponding unlabeled hormone (10-, 100-, and 1000-fold molar excess) demonstrated that (1) photoattachment of labeled T3 or T4 to the 56- and 45-kDa proteins was inhibited by 67-78% and 73-85%, respectively, after incubation with a 1000-fold molar excess of unlabeled hormone, (2) in the presence of lower molar excesses of the corresponding competitor (10- and 100-fold), photoattachment of labeled T3 or T4 to the 56- and 45-kDa receptors was gradually inhibited to a similar extent on both proteins, and (3) the 35- and 96-kDa proteins, although having thyroid hormone binding sites, display lower binding activities since the inhibition of photoattachment of labeled T3 or T4 by a 1000-fold molar excess of unlabeled hormone did not exceed 30-42% and 26-49%, respectively. Hence, only the 56- and 45-kDa proteins are thyroid hormone receptors. The similar behavior of the 56- and 45-kDa receptors in the competition studies suggests a structural relationship between the two proteins. Digestion of the 56- and 45-kDa proteins with Staphylococcus aureus V8 protease yielded virtually identical peptide patterns, indicating that both receptor proteins share homologous amino acid sequences.

AB - Photoaffinity labeling of rat liver nuclear extract with underivatized thyroid hormones was performed after incubation with 1 nM [3′,5′-125I]thyroxine ([125I]T4) or [3′-125I]triiodothyronine ([125I]T3) by irradiation with light above 300 nm. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the covalently photolabeled nuclear extract revealed four distinct hormone binding proteins of molecular masses 96, 56, 45, and 35 kilodaltons (kDa), respectively. Distribution of the hormone among these proteins was similar for T4 and T3. The 56- and 45-kDa proteins were the most prominently labeled. The specificity of the photoattachment of thyroid hormones to these nuclear proteins was verified by the irradiation of eight randomly chosen proteins and two proteins known to have thyroid hormone binding sites, human thyroxine binding globulin and bovine serum albumin. Only the latter two were photolabeled with [125I]T4. Competition studies performed by incubating nuclear extracts with [125I]T4 or [125I]T3 in the presence of increasing amounts of the corresponding unlabeled hormone (10-, 100-, and 1000-fold molar excess) demonstrated that (1) photoattachment of labeled T3 or T4 to the 56- and 45-kDa proteins was inhibited by 67-78% and 73-85%, respectively, after incubation with a 1000-fold molar excess of unlabeled hormone, (2) in the presence of lower molar excesses of the corresponding competitor (10- and 100-fold), photoattachment of labeled T3 or T4 to the 56- and 45-kDa receptors was gradually inhibited to a similar extent on both proteins, and (3) the 35- and 96-kDa proteins, although having thyroid hormone binding sites, display lower binding activities since the inhibition of photoattachment of labeled T3 or T4 by a 1000-fold molar excess of unlabeled hormone did not exceed 30-42% and 26-49%, respectively. Hence, only the 56- and 45-kDa proteins are thyroid hormone receptors. The similar behavior of the 56- and 45-kDa receptors in the competition studies suggests a structural relationship between the two proteins. Digestion of the 56- and 45-kDa proteins with Staphylococcus aureus V8 protease yielded virtually identical peptide patterns, indicating that both receptor proteins share homologous amino acid sequences.

UR - http://www.scopus.com/inward/record.url?scp=0021931791&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021931791&partnerID=8YFLogxK

M3 - Article

VL - 24

SP - 5197

EP - 5202

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 19

ER -