Reaction of the type III iodothyronine deiodinase with the affinity label N‐bromoacetyl‐triiodothyronine

FEBS Letters

Visser, Theo J.²  Pigmans, Ingrid G.A.J.²  Darras, Veerle M.¹  Schoenmakers, Christian H.H.²  Kaptein, Ellen² 

[1] Laboratory of Comparative Endocrinology, Catholic University of Leuven, B-3000 Leuven, Belgium;Department of Internal Medicine III, Erasmus University Medical School, PO Box 1738, 3000 DR Rotterdam, The Netherlands

关键词: Thyroid hormone;    lodothyronines;    Deiodination;    Rat;    Chicken;    Liver;    Placenta;    Brain;    Affinity-labelling;    Bromoacetyl derivative;   

DOI  :  10.1016/0014-5793(93)80449-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The type III iodothyronine deiodinase (ID-III) catalyzes the inner ring deiodination and, thus, the inactivation of the thyroid hormones T₄ and T₃. ID-III activity in rat brain, rat placenta and embryonic chicken liver is inhibited by the affinity label N-bromoacetyl-T₃, (BrAcT₃) with an affinity similar to that of T₃. Reaction of rat brain and placenta microsomes with BrAc[¹²⁵I]T₃ resulted in the extensive labeling of a 32 kDa protein (p32). However, p32 was also prominently labeled in fetal rat liver microsomes which have no ID-III activity. Labeling of p32 was not influenced by 100 μM substrate analogs or inhibitors of ID-III, some of which completely inhibit ID-III activity at 1 μ. BrAc[¹²⁵I]T₃, labeling of embryonic chicken liver microsomes did not reveal p32 or another protein possibly related to ID-III. In contrast to previous suggestions, it is unlikely that p32 represents ID-III or a subunit thereof.

【 授权许可】

Unknown