Tommasino M, Adamczewski J P, Carlotti F, Barth C F, Manetti R, Contorni M, Cavalieri F, Hunt T, Crawford L
Department of Pathology, University of Cambridge, UK.
Oncogene. 1993 Jan;8(1):195-202.
E7 is the major transforming protein of human papillomavirus type 16 (HPV16). It has been found to associate with the retinoblastoma protein Rb1. We investigated whether HPV16 E7 protein was associated with other cellular proteins, in particular with those involved in cell cycle control. Immunoprecipitates from CaSki cell extracts with an anti E7 monoclonal antibody contained a histone H1 kinase. Recombinant E7, synthesized in yeast, when mixed with protein extracts from epithelial cells bound histone H1 kinase activity in vitro. The in vivo and the in vitro-formed E7-kinase complex had the same periodicity of activity during the cell cycle, being most active in S and G2/M. Immunoblotting of E7 immunoprecipitates with an antibody raised against the p33CDK2, revealed a 33 kDa protein band not detected by an anti-p34cdc2 antibody, suggesting that the E7-associated kinase activity is due to the p33CDK2. The interaction appears to be via cyclin A, since probing of similar immunoblots showed a 50 kDa band corresponding to cyclin A. The association of E7 with cyclin A appeared to be direct, not involving Rb 1 or other proteins.
E7是16型人乳头瘤病毒（HPV16）的主要转化蛋白。现已发现它与视网膜母细胞瘤蛋白Rb1相关。我们研究了HPV16 E7蛋白是否与其他细胞蛋白相关，特别是与那些参与细胞周期调控的蛋白。用抗E7单克隆抗体从CaSki细胞提取物中进行免疫沉淀，沉淀物中含有组蛋白H1激酶。在酵母中合成的重组E7与上皮细胞的蛋白提取物混合后，在体外能结合组蛋白H1激酶活性。体内和体外形成的E7 - 激酶复合物在细胞周期中具有相同的活性周期，在S期和G2/M期最为活跃。用抗p33CDK2抗体对E7免疫沉淀物进行免疫印迹分析，发现一条33 kDa的蛋白带，而抗p34cdc2抗体未检测到该条带，这表明与E7相关的激酶活性是由p33CDK2引起的。这种相互作用似乎是通过细胞周期蛋白A介导的，因为对类似免疫印迹的检测显示出一条对应于细胞周期蛋白A的50 kDa条带。E7与细胞周期蛋白A的结合似乎是直接的，不涉及Rb1或其他蛋白。
