Selenocysteine-containing enzymes that have been identified in mammals include the glutathione peroxidase family (GPX1, GPX2, GPX3, and GPX4), one or more iodothyronine deiodinases and two thioredixin reductases. Selenoprotein P, a glycoprotein that contains 10 selenocysteine residues per 43 kDa polypeptide and selenoprotein W, a 10 kDa muscle protein, are unidentified as to function. Levels of all of these selenocysteine-containing proteins in various tissues are affected to different extents by selenium availability. Increased amounts of selenoproteins observed in response to selenium supplementation were shown in several studies to correlate with increases in the corresponding mRNA levels. In general, selenoprotein levels in brain are less sensitive to dietary selenium fluctuation than the corresponding selenoprotein levels in other tissues.

中文翻译：

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硒蛋白对饮食硒的反应性。

在哺乳动物中已经鉴定出的含硒代半胱氨酸的酶包括谷胱甘肽过氧化物酶家族（GPX1，GPX2，GPX3和GPX4），一种或多种碘甲状腺素脱碘酶和两种硫氧还蛋白还原酶。硒蛋白P（一种糖蛋白，每43 kDa多肽含有10个硒代半胱氨酸残基）和硒蛋白W（一种10 kDa的肌肉蛋白）尚未发挥作用。硒的可利用性在不同组织中对所有这些含硒代半胱氨酸的蛋白质的水平产生不同程度的影响。多项研究表明，对硒补充的反应中观察到的硒蛋白含量增加与相应的mRNA水平增加相关。通常，与其他组织中相应的硒蛋白水平相比，大脑中的硒蛋白水平对饮食中硒的波动较不敏感。