Lu Jun, Holmgren Arne
Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-17177 Stockholm, Sweden.
J Biol Chem. 2009 Jan 9;284(2):723-7. doi: 10.1074/jbc.R800045200. Epub 2008 Aug 29.
Selenium is an essential micronutrient for man and animals. The role of selenium has been attributed largely to its presence in selenoproteins as the 21st amino acid, selenocysteine (Sec, U). Sec is encoded by TGA in DNA. A unique mechanism is used to decode the UGA codon in mRNA to co-translationally incorporate Sec into the growing polypeptide because there is no free pool of Sec. In the human genome, 25 genes for selenoproteins have been identified. Selenoproteins such as glutathione peroxidases, thioredoxin reductases, and iodothyronine deiodinases are involved in redox reactions, and Sec is an active-site residue essential for catalytic activity. Selenoproteins have biological functions in oxidoreductions, redox signaling, antioxidant defense, thyroid hormone metabolism, and immune responses. They thus possess a strong correlation with human diseases such as cancer, Keshan disease, virus infections, male infertility, and abnormalities in immune responses and thyroid hormone function.
硒是人和动物必需的微量营养素。硒的作用很大程度上归因于它作为第21种氨基酸——硒代半胱氨酸（Sec，U）存在于硒蛋白中。Sec在DNA中由TGA编码。由于不存在游离的Sec库，因此使用一种独特的机制来解码mRNA中的UGA密码子，以便在共翻译过程中将Sec掺入正在生长的多肽中。在人类基因组中，已鉴定出25个硒蛋白基因。谷胱甘肽过氧化物酶、硫氧还蛋白还原酶和碘甲状腺原氨酸脱碘酶等硒蛋白参与氧化还原反应，Sec是催化活性所必需的活性位点残基。硒蛋白在氧化还原、氧化还原信号传导、抗氧化防御、甲状腺激素代谢和免疫反应中具有生物学功能。因此，它们与癌症、克山病、病毒感染、男性不育以及免疫反应和甲状腺激素功能异常等人类疾病密切相关。
