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Licensed Unlicensed Requires Authentication Published by De Gruyter June 1, 2005

The Effects of Endocrine-Disrupting Chemicals on Thyroid Hormone Binding to Xenopus laevis Transthyretin and Thyroid Hormone Receptor

Kiyoshi Yamauchi , Ryoji Eguchi , Naoyuki Shimada and Akinori Ishihara
From the journal

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-β (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 104 times greater than that of unlabeled T3. These results indicate the existence of several chemicals that interact with xTTR but not with xTR LBD.

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Published Online: 2005-06-01
Published in Print: 2002-12-10

Copyright © 2002 by Walter de Gruyter GmbH & Co. KG

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