Structural analysis of the human U3 ribonucleoprotein particle reveal a conserved sequence available for base pairing with pre-rRNA.
Structural analysis of the human U3 ribonucleoprotein particle reveal a conserved sequence available for base pairing with pre-rRNA.
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人 U3 核糖核蛋白颗粒的结构分析揭示了可与 pre-rRNA 碱基配对的保守序列。
DOI：
10.1128/mcb.7.8.2899-2913.1987
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发表时间：
1987
影响因子：
5.3
通讯作者：
Steitz,JA
中科院分区：
文献类型：
--
作者：
Parker,KA;Steitz,JA
对人U3核糖核蛋白（RNP）进行了分析，以确定其蛋白质成分、蛋白-RNA相互作用位点和RNA二级结构。通过抗u3 RNP抗体和体内标记的HeLa细胞提取物，发现RNP含有4个36、30、13和12.5千道尔顿的非磷酸化蛋白和2个74和59千道尔顿的磷酸化蛋白。U3核苷酸72-90、106-121、154-166和190-217必须包含与蛋白质相互作用的位点，因为这些区域在RNP用RNase A或T1处理后被免疫沉淀。二级结构用特异性核酸酶探测，用单链特异性试剂进行化学修饰，阻断随后的逆转录。单链区域（因此可能与底物RNA相互作用）包括核苷酸104-112处的进化保守序列和核苷酸65-74、80-84和88-93处的非保守序列。核苷酸159-168似乎不是高度可接近的，因此不太可能像先前提出的那样，该U3序列碱基对与5.8S rrna -内部转录间隔器II连接处附近的序列配对。讨论了U3 RNP的其他功能，包括U3可能参与28S rRNA 3 '端附近的加工事件的可能性。
The human U3 ribonucleoprotein (RNP) has been analyzed to determine its protein constituents, sites of protein-RNA interaction, and RNA secondary structure. By using anti-U3 RNP antibodies and extracts prepared from HeLa cells labeled in vivo, the RNP was found to contain four nonphosphorylated proteins of 36, 30, 13, and 12.5 kilodaltons and two phosphorylated proteins of 74 and 59 kilodaltons. U3 nucleotides 72-90, 106-121, 154-166, and 190-217 must contain sites that interact with proteins since these regions are immunoprecipitated after treatment of the RNP with RNase A or T1. The secondary structure was probed with specific nucleases and by chemical modification with single-strand-specific reagents that block subsequent reverse transcription. Regions that are single stranded (and therefore potentially able to interact with a substrate RNA) include an evolutionarily conserved sequence at nucleotides 104-112 and nonconserved sequences at nucleotides 65-74, 80-84, and 88-93. Nucleotides 159-168 do not appear to be highly accessible, thus making it unlikely that this U3 sequence base pairs with sequences near the 5.8S rRNA-internal transcribed spacer II junction, as previously proposed. Alternative functions of the U3 RNP are discussed, including the possibility that U3 may participate in a processing event near the 3′ end of 28S rRNA.