Imai Y, Matsushima Y, Sugimura T, Terada M
Genetics Division, National Cancer Center Research Institute, Tokyo, Japan.
J Virol. 1991 Sep;65(9):4966-72. doi: 10.1128/JVI.65.9.4966-4972.1991.
Human papillomavirus type 16 E7 is considered to be a major viral oncoprotein playing an important role(s) in cervical cancers. E7 protein was shown to bind to the protein product of the retinoblastoma gene (RB), while simian virus 40 large T and adenovirus E1A were also shown to possess binding activity to RB protein. The RB protein is a cell cycle regulator that is highly phosphorylated specifically in S, G2, and M, whereas it is underphosphorylated in G0 and G1. Recently, large T was demonstrated to bind preferentially to the underphosphorylated RB protein, which is considered to be an active form restricting cell proliferation. However, it is not known whether E7 can bind to phosphorylated RB protein. We successfully purified large quantities of unfused human papillomavirus type 16 E7 protein expressed in Escherichia coli by using a T7 promoter-T7 RNA polymerase system. The purified E7 protein was demonstrated to bind preferentially to the underphosphorylated RB protein.
人乳头瘤病毒16型E7被认为是一种主要的病毒癌蛋白，在宫颈癌中发挥重要作用。E7蛋白被证明可与视网膜母细胞瘤基因（RB）的蛋白产物结合，而猴病毒40大T抗原和腺病毒E1A也被证明对RB蛋白具有结合活性。RB蛋白是一种细胞周期调节因子，在S期、G2期和M期高度磷酸化，而在G0期和G1期磷酸化不足。最近，大T抗原被证明优先结合磷酸化不足的RB蛋白，该蛋白被认为是限制细胞增殖的活性形式。然而，尚不清楚E7是否能与磷酸化的RB蛋白结合。我们通过使用T7启动子-T7 RNA聚合酶系统，成功地在大肠杆菌中纯化了大量未融合的人乳头瘤病毒16型E7蛋白。纯化的E7蛋白被证明优先结合磷酸化不足的RB蛋白。
