FUNCTIONAL-CHARACTERIZATION OF THE EUKARYOTIC SECIS ELEMENTS WHICH DIRECT SELENOCYSTEINE INSERTION AT UGA CODONS
FUNCTIONAL-CHARACTERIZATION OF THE EUKARYOTIC SECIS ELEMENTS WHICH DIRECT SELENOCYSTEINE INSERTION AT UGA CODONS
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DOI：
10.1002/j.1460-2075.1993.tb06001.x
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发表时间：
1993-08-01
期刊：
影响因子：
11.4
通讯作者：
LARSEN, PR
中科院分区：
文献类型：
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作者：
BERRY, MJ;BANU, L;LARSEN, PR
我们研究了硒代半胱氨酸插入在真核生物硒蛋白中的单个或多个UGA密码子的要求。在大鼠硒蛋白P mRNA的3'非翻译区中鉴定出两个功能性SECIS元件，其预测的茎环和关键核苷酸与I型碘甲状腺原氨酸5'脱碘酶（5'DI）和谷胱甘肽过氧化物酶硒蛋白mRNA中的SECIS元件相似。三个SECIS元件的定点突变分析证实，保守的核苷酸在环中，并在未配对的区域的干是至关重要的活动。这表明SECIS功能需要多个接触点。5 ′ DI mRNA中5个背景外UGA密码子中任何一个的终止密码子功能都被连接在下游的5 ′ DI或硒蛋白P基因的SECIS元件抑制。因此，真核硒蛋白mRNA中SECIS元件的存在允许UGA密码子位置完全灵活。
We investigated the requirements for selenocysteine insertion at single or multiple UGA codons in eukaryotic selenoproteins. Two functional SECIS elements were identified in the 3' untranslated region of the rat selenoprotein P mRNA, with predicted stem-loops and critical nucleotides similar to those in the SECIS elements in the type I iodothyronine 5' deiodinase (5'DI) and glutathione peroxidase selenoprotein mRNAs. Site-directed mutational analyses of three SECIS elements confirmed that conserved nucleotides in the loop and in unpaired regions of the stem are critical for activity. This indicates that multiple contact sites are required for SECIS function. Stop codon function at any of five out-of-context UGA codons in the 5'DI mRNA was suppressed by SECIS elements from the 5'DI or selenoprotein P genes linked downstream. Thus, the presence of SECIS elements in eukaryotic selenoprotein mRNAs permits complete flexibility in UGA codon position.