Asano K, Merrick W C, Hershey J W
Department of Biological Chemistry, School of Medicine, University of California, Davis, California 95616, USA.
J Biol Chem. 1997 Sep 19;272(38):23477-80. doi: 10.1074/jbc.272.38.23477.
Translation initiation factor eIF3 is a large, multisubunit protein complex that plays a central role in the pathway of initiation by promoting the binding of both methionyl-tRNAi and mRNA to the 40S ribosomal subunit. As part of a broad effort to elucidate the structure of eIF3, we have cloned and sequenced the human cDNA encoding the 48-kDa subunit, eIF3-p48. The recombinant protein comigrates with the authentic p48 subunit in purified eIF3 and coprecipitates with affinity-purified antibodies to the p170 subunit of eIF3. A search of the data base indicates that the mouse gene encoding eIF3-p48 had previously been identified and characterized by others as int-6. The int-6 gene is the site of frequent integration of mouse mammary tumor virus DNA into chromosomes, implicating the gene in the regulation of cell proliferation. In addition, it was shown elsewhere that the homologous human int-6 gene product binds to the human T-cell leukemia virus type I Tax protein, leading to the translocation of Int-6 to the cytoplasm. We discuss how the cytosolic function of eIF3-p48 (Int-6) in protein synthesis may account for oncogenesis caused by these two viruses.
翻译起始因子eIF3是一种大型多亚基蛋白复合物，通过促进甲硫氨酰 - tRNAi和mRNA与40S核糖体亚基的结合，在起始途径中发挥核心作用。作为阐明eIF3结构的广泛努力的一部分，我们克隆并测序了编码48 kDa亚基eIF3 - p48的人cDNA。重组蛋白在纯化的eIF3中与天然p48亚基共迁移，并与针对eIF3的p170亚基的亲和纯化抗体共沉淀。数据库搜索表明，编码eIF3 - p48的小鼠基因先前已被其他人鉴定并表征为int - 6。int - 6基因是小鼠乳腺肿瘤病毒DNA频繁整合到染色体中的位点，这表明该基因参与细胞增殖的调节。此外，其他地方还表明，同源的人int - 6基因产物与人类I型T细胞白血病病毒Tax蛋白结合，导致Int - 6易位至细胞质。我们讨论了eIF3 - p48（Int - 6）在蛋白质合成中的胞质功能如何解释这两种病毒引起的肿瘤发生。
