Search of cellular protein(s) binding to the similar structure of HBV epsilon and HCV3'X

乙型肝炎病毒（HBV）和丙型肝炎病毒（HCV）的基因组结构和复制机制不同，但这两种病毒具有共同的生物学特性；两者都以RNA的形式作为复制媒介，2)都是嗜肝的。3)不是直接的细胞病变，但引起肝脏持续炎症，易发生肝细胞癌（HCC）。HBV RNA的Epsilon结构和HCV RNA的3'X结构对于这些病毒的复制或包装是必不可少的。我们报道了相似的二级结构，在两个结构中含有相同的7个碱基，并假设生物相似性归因于这种结构相似性。作为验证这一假设的步骤之一，我们搜索了识别这种共同结构的细胞蛋白。通过sds -southwest方法，110 kDa、35 kDa和15 kDa蛋白被这种共同结构形式的RNA或DNA寡聚物结合。其中35kda蛋白的结合信号最强。为了鉴定这些蛋白，我们用西南法检测了由HepG2 cDNA构建的60万个lambda gt11表达文库的结合活性。我们分离了4个独立克隆。其中一个是核糖体结合蛋白L5，其大小为34 kDa，与预期大小相符。我们也在分析另外3个克隆体。我们未来的任务是研究这些蛋白对HBV或HCV复制的影响。

The genomic structures and replication mechanisms of hepatitis B virus (HBV) and hepatitis C virus (HCV) are different, but these two viruses share the biological characteristics; Both 1) take the form of RNA as the replicative intermediates, 2) are hepatotropic. 3) are not directly cytopathic but cause the persistent inflammation of the liver, predisposing occurrence of hepatocellular carcinoma (HCC). Epsilon structure of HBV RNA and 3'X structure of HCV RNA are indispensable for the replication or packaging of these viruses. We reported the similar secondary structures containing the identical 7 bases in both structures, and hypothesized that the biological similarity attributes to this structural similarity. As one of the steps to verify the hypothesis, we searched the cellular protein(s) recognizing this common structure. By SDS-southwestern method, 110 kDa, 35 kDa, and 15 kDa proteins were bound by the RNA or DNA oligomeres taking the form of this common structure. Of these 3 proteins, that of 35 kDa showed the strongest binding signal. To identify these protein(s), we examined the binding activity of 600 thousand clones of lambda gt11 expression libraries constructed from HepG2 cDNA by southwestern method. We isolated 4 independent clones. One of them was ribosomal binding protein L5 which was 34 kDa and compatible to the expected size. We are also analyzing other 3 clones. Our future task is to study the effect of these proteins on the replication of HBV or HCV.