Host factors required for internal initiation of translation on poliovirus RNA

脊髓灰质炎病毒(PV)RNA的翻译是由核糖体进入核苷酸序列(内部核糖体进入位点；IRES)启动的，位于5‘-非翻译区(5’-UTR)，包含5个茎环(SL)结构。这种翻译启动在兔网织红细胞裂解物(RRL)中的效率很低，而加入从HeLa细胞制备的核糖体盐洗部分(RSW)后，效率大大提高。这种刺激活性被部分纯化，其相对分子质量估计在240,000以上。在这个脊髓灰质炎病毒IRES中检测到了几种与这些SL结构特异结合的蛋白质。其中，一个57 kDa的蛋白可被多吡啶结合蛋白(PTB)抗体识别，另一个40 kDa的蛋白(P40)可与SLV结合。此外，36 kDa(P36)和80 kDa(P80)的蛋白与SLV特异结合。P36和p80的纯化工作正在进行中。

Translation of poliovirus (PV) RNA is initiated by entry of ribosomes into the nucleotide sequence (internal ribosomal entry site ; IRES) with in the 5'-untranslated region (5'-UTR) and contains 5 stem loop (SL) structures. Efficiency of this translation initiation in rabbit reticulocyte lysates (RRL) was very poor and was greatly enhanced by the addition of the ribosomal salt-wash fraction (RSW) prepared from HeLa cells. This stimulation activity in the RSW was partially purified and its molecular weight was estimated to be more than 240,000. Several proteins that bind spoecifically to these SL structures in this poliovirus IRES were detected. Among those, a 57 kDa protein, recognized by antibodies against polypyrimidide tract-binding protein (PTB), and a 40 kDa protein (p40) which is identified as PCBP2 (polyC binding protein) bound to SLIV.In addition, 36 kDa (p36) and 80kDa (p80) proteins bind to SLV spesifically. The purification of p36 and p80 are now on progress.