Valverde C, Croteau W, Lafleur G J, Orozco A, Germain D L
Universidad National Autonoma de Mexico, Mexico, D. F.
Endocrinology. 1997 Feb;138(2):642-8. doi: 10.1210/endo.138.2.4904.
Recent molecular cloning studies in mammals and amphibians have demonstrated that the types I, II, and III deiodinases constitute a family of selenoproteins of critical importance in metabolizing T4 to active (i.e. T3) and inactive (i.e. rT3) metabolites. In several tissues of teleost fish, various deiodinase processes have been described, but the structural and functional characteristics of these enzymes and their relationship to the deiodinases present in higher vertebrates remains uncertain. Using a complementary DNA library derived from the liver of the teleost Fundulus heteroclitus, we have identified a complementary DNA that codes for a deiodinase with functional characteristics virtually identical to those of the mammalian and amphibian type II deiodinase. Sequence analysis demonstrates a high degree of homology at both the nucleotide and predicted amino acid levels between the Fundulus clone and these previously characterized type II enzymes, including the presence of an in-frame TGA codon that codes for selenocysteine. These findings demonstrate that the deiodinase family of selenoproteins has been highly conserved during vertebrate evolution and underscores their importance in the regulation of thyroid hormone action.
最近在哺乳动物和两栖动物中进行的分子克隆研究表明，I型、II型和III型脱碘酶构成了一个硒蛋白家族，在将T4代谢为活性（即T3）和非活性（即反T3）代谢物方面至关重要。在硬骨鱼的多个组织中，已经描述了各种脱碘酶过程，但这些酶的结构和功能特征以及它们与高等脊椎动物中存在的脱碘酶的关系仍不确定。利用从硬骨鱼异鳞底鳉肝脏中获得的互补DNA文库，我们鉴定出了一个互补DNA，它编码一种脱碘酶，其功能特征与哺乳动物和两栖动物的II型脱碘酶几乎相同。序列分析表明，底鳉克隆与这些先前表征的II型酶在核苷酸和预测氨基酸水平上都具有高度同源性，包括存在一个编码硒代半胱氨酸的框内TGA密码子。这些发现表明，硒蛋白脱碘酶家族在脊椎动物进化过程中高度保守，并强调了它们在甲状腺激素作用调节中的重要性。
