Carroll S B, Stollar B D
J Mol Biol. 1983 Nov 5;170(3):777-90. doi: 10.1016/s0022-2836(83)80131-4.
Using a monoclonal antibody to a DNA-binding site of calf RNA polymerase II, we found that this site occurs on the largest subunit and is structurally similar in RNA polymerase II of widely divergent eukaryotes. In immuno-blotting of electrophoretically separated subunits, the monoclonal antibody recognized a determinant on the largest polypeptide of all RNA eukaryotic polymerase II forms tested, with a preference for the IIA enzyme subunit of 215 X 10(3) Mr over the partially proteolyzed 180 X 10(3) Mr form. This site is conserved on human, chicken, Drosophila, wheat germ and yeast RNA polymerase II, all of which reacted strongly with the monoclonal antibody. These results contrasted with those obtained with polyclonal antibodies to non-functional determinants of the calf enzyme. The reactivity of the polyclonal antibody with eukaryotic RNA polymerase II steadily decreased with increasing evolutionary distance from the original antigen; the yeast enzyme showed no cross-reactivity. These results suggest that a basic functional feature of eukaryotic RNA polymerase II has been strongly conserved and support the view that divergence of RNA polymerase II has taken place mainly in other, perhaps regulatory, sites of the enzyme.
利用针对小牛RNA聚合酶II的一个DNA结合位点的单克隆抗体，我们发现该位点存在于最大亚基上，并且在广泛不同的真核生物的RNA聚合酶II中结构相似。在对电泳分离的亚基进行免疫印迹时，该单克隆抗体识别了所有测试的真核生物RNA聚合酶II形式的最大多肽上的一个决定簇，相较于部分经蛋白酶水解的180×10³Mr形式，它更倾向于识别215×10³Mr的IIA酶亚基。该位点在人、鸡、果蝇、小麦胚芽和酵母的RNA聚合酶II上保守，所有这些都与该单克隆抗体发生强烈反应。这些结果与用针对小牛酶的无功能决定簇的多克隆抗体所获得的结果形成对比。多克隆抗体与真核生物RNA聚合酶II的反应性随着与原始抗原进化距离的增加而稳步下降；酵母酶没有交叉反应性。这些结果表明真核生物RNA聚合酶II的一个基本功能特征得到了强烈保守，并支持这样一种观点，即RNA聚合酶II的分化主要发生在该酶的其他位点，可能是调控位点。
