THE RIBOSOMAL L5 PROTEIN IS ASSOCIATED WITH MDM-2 AND MDM-2-P53 COMPLEXES
THE RIBOSOMAL L5 PROTEIN IS ASSOCIATED WITH MDM-2 AND MDM-2-P53 COMPLEXES
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DOI：
10.1128/mcb.14.11.7414
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发表时间：
1994-11-01
影响因子：
5.3
通讯作者：
LEVINE, AJ
中科院分区：
文献类型：
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作者：
MARECHAL, V;ELENBAAS, B;LEVINE, AJ
在对MDM-2或MDM-2-P53蛋白复合体的纯化过程中，观察到一种相对分子质量为34,000的蛋白质与这些蛋白质结合。针对MDM-2或P53蛋白中不同表位的几种单抗共免疫沉淀了这一34000分子量的蛋白，该蛋白与Western免疫印迹中的P53或MDM-2多克隆抗血清不发生反应。这个34,000分子量的蛋白质的N末端氨基酸序列表明，前40个氨基酸与核糖体L5蛋白相同，L5蛋白存在于大的rRNA亚基中，并与5S RNA结合。正品L5蛋白和34000分子量蛋白的部分肽图完全相同。MDM-2-L5和MDM-2-L5-P53复合体与5S RNA特异性结合，可能是通过L5蛋白与5S RNA的特异性结合。在5S RNA-L5-MDM-2-P53核糖核蛋白复合体中，也可以检测到5.8S RNA，它被认为与细胞中一定比例的P53蛋白共价连接。这些实验已经确定了一个独特的核糖核蛋白复合体，它由5S RNA、L5蛋白、MDM-2蛋白、P53蛋白以及可能的5.8S RNA组成。虽然这种核糖核蛋白复合体的功能尚不清楚，但其组成成分的一致性表明，这些蛋白质和RNA物种在核糖体的生物发生、核糖体从核到细胞质的运输或细胞内的翻译调节中发挥了作用。
Throughout the purification of the mdm-2 or mdm-2-p53 protein complexes, a protein with a molecular weight of 34,000 was observed to copurify with these proteins. Several monoclonal antibodies directed against distinct epitopes in the mdm-2 or p53 protein coimmunoprecipitated this 34,000 molecular-weight protein, which did not react to p53 or mdm-2 polyclonal antisera in a Western immunoblot. The N-terminal amino acid sequence of this 34,000-molecular-weight protein demonstrated that the first 40 amino acids were identical to the ribosomal L5 protein, found in the large rRNA subunit and bound to 5S RNA. Partial peptide maps of the authentic L5 protein and the 34,000-molecular-weight protein were identical. mdm-2-L5 and mdm-2-L5-p53 complexes were shown to bind 5S RNA specifically, presumably through the known specificity of L5 protein for 5S RNA. In 5S RNA-L5-mdm-2-p53 ribonucleoprotein complexes, it was also possible to detect the 5.8S RNA which has been suggested to be covalently linked to a percentage of the p53 protein in a cell. These experiments have identified a unique ribonucleoprotein complex composed of 5S RNA, L5 protein, mdm-2 proteins, p53 protein, and possibly the 5.8S RNA. While the function of such a ribonucleoprotein complex is not yet clear, the identity of its component parts suggests a role for these proteins and RNA species in ribosomal biogenesis, ribosomal transport from the nucleus to the cytoplasm, or translational regulation in the cell.