Herrmann C H, Su L K, Harlow E
Cold Spring Laboratory, New York 11724.
J Virol. 1991 Nov;65(11):5848-59. doi: 10.1128/JVI.65.11.5848-5859.1991.
The adenovirus E1A proteins form stable protein complexes with a number of cellular proteins, including cyclin A and the product of the retinoblastoma susceptibility gene. We have been interested in learning about the function of proteins associated with E1A and therefore looked for an enzymatic activity present in E1A complexes. We found a serine/threonine kinase activity that phosphorylates two proteins bound to E1A, the 107- and 130-kDa (107K and 130K) proteins. The kinase also phosphorylates histone H1 added as an exogenous substrate. The kinase activity is cell cycle regulated, being most active in S and G2/M-phase cells. The timing of phosphorylation of the 107K protein in vitro correlates with the phosphorylation pattern of the 107K protein in vivo. A variety of genetic and immunochemical approaches indicate that the activity is probably not due to the E1A-associated 300K, 130K, 107K, or pRB protein. Although we have not established the identity of the kinase, we present evidence that the kinase activity is consistent with phosphorylation by p34cdc2 or a related kinase.
腺病毒E1A蛋白可与多种细胞蛋白形成稳定的蛋白复合物，这些细胞蛋白包括细胞周期蛋白A和视网膜母细胞瘤易感基因的产物。我们一直对了解与E1A相关的蛋白的功能感兴趣，因此寻找E1A复合物中存在的酶活性。我们发现了一种丝氨酸/苏氨酸激酶活性，它可使与E1A结合的两种蛋白，即107-kDa和130-kDa（107K和130K）蛋白发生磷酸化。该激酶还可使作为外源底物添加的组蛋白H1发生磷酸化。激酶活性受细胞周期调控，在S期和G2/M期细胞中最为活跃。体外107K蛋白的磷酸化时间与体内107K蛋白的磷酸化模式相关。多种遗传学和免疫化学方法表明，该活性可能不是由与E1A相关的300K、130K、107K或pRB蛋白所致。尽管我们尚未确定该激酶的身份，但我们提供的证据表明，该激酶活性与p34cdc2或相关激酶的磷酸化作用一致。
