Gutiérrez-Escolano L, del Angel R M
Departamento de Patología Experimental, Centro de Investigación y de Estudios Avanzados del IPN, México, D.F.
Arch Med Res. 1996 Autumn;27(3):413-9.
Poliovirus induces a shut-off of messenger RNA (mRNA) translation by the proteolysis of a 220 kDa protein from the eukaryotic initiation factor eIF-4F, and by the phosphorylation of eIF-2. The absence of eIF-4F inhibits the initiation of translation dependent on cap structure recognition. Poliovirus RNA lacks cap structure and translates by a cap-independent mechanism which requires internal ribosomal entry. The poliovirus 5' untranslated region (5'UTR) contains the structural elements for cap-independent translation called internal ribosomal entry site (IRES element). Several cellular proteins have been described interacting with different segments from poliovirus 5'UTR. We have studied the specific interaction between 57/60, 52, and 35 kDa cellular proteins with poliovirus nt 275 to 636 and full length 5'UTR. By Western blot assay the 57/60 protein was identified as a pyrimidine tract binding protein (PTB), and the 52 kDa protein as a La-autoantigen. La and PTB are nuclear proteins involved in RNA polymerase III transcription termination and splicing, respectively.
脊髓灰质炎病毒通过对真核起始因子eIF - 4F的一种220 kDa蛋白进行蛋白水解以及使eIF - 2磷酸化，诱导信使核糖核酸（mRNA）翻译的关闭。eIF - 4F的缺失会抑制依赖帽结构识别的翻译起始。脊髓灰质炎病毒RNA缺乏帽结构，通过一种不依赖帽的机制进行翻译，这种机制需要核糖体内部进入。脊髓灰质炎病毒5'非翻译区（5'UTR）包含用于不依赖帽翻译的结构元件，称为核糖体内部进入位点（IRES元件）。已经描述了几种细胞蛋白与脊髓灰质炎病毒5'UTR的不同片段相互作用。我们研究了57/60 kDa、52 kDa和35 kDa细胞蛋白与脊髓灰质炎病毒核苷酸275至636以及全长5'UTR之间的特异性相互作用。通过蛋白质印迹分析，57/60 kDa蛋白被鉴定为嘧啶序列结合蛋白（PTB），52 kDa蛋白被鉴定为La自身抗原。La和PTB分别是参与RNA聚合酶III转录终止和剪接的核蛋白。
