Overexpression in COS cells of p50, the major core protein associated with mRNA, results in translation inhibition
Overexpression in COS cells of p50, the major core protein associated with mRNA, results in translation inhibition
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DOI：
10.1093/nar/25.14.2911
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发表时间：
1997-07-15
影响因子：
14.9
通讯作者：
Hershey, JWB
中科院分区：
文献类型：
--
作者：
Davydova, EK;Evdokimova, VM;Hershey, JWB
p50是哺乳动物体细胞胞质中信使核糖核蛋白颗粒（mRNP）的主要核心蛋白，先前已被表征为Y盒结合转录因子蛋白家族的成员（YB-蛋白）通过高结构同源性和特异性结合双链DNA中的Y盒序列的能力，YB蛋白存在于整个范围的细胞类型中，并且一些已被鉴定为细菌特异性细胞质蛋白，其掩蔽储存的mRNA使其不能翻译，COS-1细胞亚细胞组分中p50分布的Western印迹分析表明，p50是一种与mRNA定量相关的胞质蛋白，在多聚核糖体和游离mRNP中均如此，通过Western免疫印迹法测定COS-1细胞中p50的水平为总蛋白的0.10%，其几乎与核糖体的水平等摩尔，并且比mRNA水平高5-10倍。用p50表达载体瞬时转染COS-1细胞导致蛋白合成的显著抑制，用表达p50移码突变体的载体进行对照转染不会引起翻译抑制，因此p50蛋白水平的增加是这些细胞中抑制作用的原因。
p50, the major core protein of messenger ribonucleoprotein particles (mRNPs) in the cytoplasm of somatic mammalian cells, has been characterized previously as a member of the Y-box binding transcription factor family of proteins (YB-protein) by both high structural homology and ability to bind specifically the Y-box sequence in double-stranded DNA, YB proteins are present in a whole range of cell types and some have been identified as germ-specific cytoplasmic proteins masking stored mRNA from translation, Western blot analysis of the distribution of p50 in subcellular fractions of COS-1 cells shows that p50 is a cytoplasmic protein quantitatively associated with mRNA, both in polyribosomes and in free mRNPs, The level of p50 in COS-1 cells determined by Western immunoblotting is 0.10% of total protein, which is nearly equimolar to that of ribosomes and is similar to 5-10-fold higher than the mRNA level, Transient transfection of COS-1 cells with a p50-expressing vector results in a dramatic inhibition of protein synthesis, A control transfection with a vector expressing a frameshift mutant of p50 does not cause translation inhibition, Therefore the increase in p50 protein level is responsible for the inhibitory effect in these cells.