title: The effects of endocrine-disrupting chemicals on thyroid hormone binding to Xenopus laevis transthyretin and thyroid hormone receptor.
abstract: We investigated the effects of medical, industrial and agricultural chemicals on 3,3',5-L-[125I]triiodothyronine ([125I]T3) binding to purified recombinant Xenopus laevis (X. laevis) transthyretin (xTTR), a plasma thyroid hormone-binding protein, and to the ligand-binding domain of thyroid hormone receptor-beta (xTR LBD). xTTR derived from X. laevis serum had about 80 times higher affinity for T3 than for L-thyroxine. The xTTR's relative affinities for diethylstilbestrol, pentachlorophenol and ioxynil were 10(-1)- to 10(-2)-fold less than that for T3. However, all chemicals investigated had either a weak or no influence on [125I]T3 binding to xTR LBD. The concentration of diethylstilbestrol, the most potent chemical, required for 50% inhibition of [125I]T3 binding to xTR LBD was 10(4) times greater than that of unlabeled T3. These results indicate the existence of several chemicals that interact with xTTR but not with xTR LBD.
authors.affiliation: Department of Biology and Geoscience, Faculty of Science, Shizuoka University, Shizuoka, Japan. sbkyama@ipc.shizuoka.ac.jp
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Yamauchi
authors.forename: Ryoji
authors.initials: R
authors.lastname: Eguchi
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Shimada
authors.forename: Akinori
authors.initials: A
authors.lastname: Ishihara
mesh_terms: D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D004703:Endocrine System / Q000187:drug effects*; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D066298:In Vitro Techniques; D011228:Prealbumin / Q000378:metabolism*; D011988:Receptors, Thyroid Hormone / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013963:Thyroid Hormones / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D004968:Estrogens, Non-Steroidal; D011228:Prealbumin; D011988:Receptors, Thyroid Hormone; D011994:Recombinant Proteins; D013963:Thyroid Hormones