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5'-非翻译区（5'-UTR）的核苷酸序列（内部核糖体进入位点；IRES）开始的，包含5个茎环（SL）结构。兔网织细胞裂解物（RRL）的翻译起始效率很低，加入HeLa细胞制备的核糖体盐洗部分（RSW）后，翻译起始效率大大提高。RSW中的这种刺激活性被部分纯化，其分子量估计超过240,000。在脊髓灰质炎病毒IRES中检测到几种与这些SL结构特异性结合的蛋白质。其中，一个57 kDa的蛋白被polypyrimidiide tract-binding protein （PTB）抗体识别，另一个40 kDa的蛋白被鉴定为与SLIV结合的PCBP2 （polyC binding protein）。此外，36 kDa （p36）和80kDa （p80）蛋白特异性结合SLV。p36和p80的净化工作正在进行中。

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.