Zandomeni R, Weinmann R
J Biol Chem. 1984 Dec 10;259(23):14804-11.
The adenosine analog 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) inhibits specific in vitro transcription initiation by RNA polymerase II. We report here that DRB inhibits a protein kinase present in an extract of HeLa cells and does not inhibit other protein kinases contained in the same extract. The protein kinase affected by DRB is cyclic AMP independent, prefers acidic protein substrates such as casein and phosvitin, and utilizes GTP as the phosphate donor almost as effectively as ATP in the phosphotransferase reaction. The DRB-sensitive protein kinase is also stimulated by polyamines and inhibited by quercitin and heparin. The biochemical and chromatographic properties of this enzyme correspond to those characteristic of casein kinase II. In HeLa cells, DRB is able to inhibit in vivo phosphorylation on some nuclear proteins. In HeLa cell extracts, in vitro phosphorylation of several proteins by [gamma-32P]GTP is inhibited by DRB. This protein kinase has a DRB sensitivity profile identical to the one previously reported for specific in vitro transcription by RNA polymerase II in a whole-cell extract (Zandomeni, R., Mittleman, B., Bunick, D., Ackerman, S., and Weinmann, R. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 3167-3170). Thus we suggest that this protein kinase mediates DRB inhibition of specific RNA polymerase II transcription in vivo and in vitro.
腺苷类似物5,6-二氯-1-β-D-呋喃核糖基苯并咪唑（DRB）可抑制RNA聚合酶II在体外的特异性转录起始。我们在此报告，DRB可抑制HeLa细胞提取物中存在的一种蛋白激酶，而不抑制同一提取物中所含的其他蛋白激酶。受DRB影响的蛋白激酶不依赖环磷酸腺苷（cAMP），更倾向于酸性蛋白底物，如酪蛋白和卵黄高磷蛋白，并且在磷酸转移酶反应中利用GTP作为磷酸供体的效率几乎与ATP相同。对DRB敏感的蛋白激酶也受到多胺的刺激，并被槲皮素和肝素抑制。这种酶的生化和色谱特性与酪蛋白激酶II的特性相符。在HeLa细胞中，DRB能够抑制某些核蛋白的体内磷酸化。在HeLa细胞提取物中，DRB可抑制[γ-32P]GTP对几种蛋白的体外磷酸化。这种蛋白激酶对DRB的敏感性谱与先前报道的全细胞提取物中RNA聚合酶II特异性体外转录的敏感性谱相同（赞多梅尼，R.，米特尔曼，B.，布尼克，D.，阿克曼，S.，和温曼，R.（1982年）《美国国家科学院院刊》79，3167 - 3170）。因此我们认为，这种蛋白激酶在体内和体外介导DRB对RNA聚合酶II特异性转录的抑制作用。
