Detke S, Paule M R
Biochim Biophys Acta. 1978 Aug 23;520(1):131-8. doi: 10.1016/0005-2787(78)90014-x.
Multiple forms of class III DNA-dependent RNA polymerase have been found in a number of higher eukaryotic cells types (Chambon, P. (1975) Annu. Rev. Biochem. 44, 613--638). Similar multiple forms are reported here from a lower eukaryote, the soil amoeba Acanthamoeba castellanii. The levels of activity of all three RNA polymerase classes in whole cell extracts of Acanthamoeba during cellular differentiation were examined. In contrast to our previous observation (Detke, S. and Paule, M.R. (1975) Biochim. Biophys. Acta 383, 67--77) that the amount of the alpha-amanitin-sensitive polymerases (II + III) increase in the nucleus during encystment we find that the amount of polymerases II and III when solubilized from whole cells remains constant. The level of activity of polymerase I, however, remains constant both in nuclei and in whole cell extracts. Thus, the shutdown of ribosomal RNA synthesis occurring during encystment is not due to a decrease in the number of polymerase I molecules in the cell.
在许多高等真核细胞类型中已发现多种形式的III类DNA依赖性RNA聚合酶（尚邦，P.（1975年）《生物化学年度评论》44卷，613 - 638页）。本文报道了来自一种低等真核生物——土壤变形虫卡氏棘阿米巴的类似多种形式。研究了卡氏棘阿米巴细胞分化过程中全细胞提取物中所有三种RNA聚合酶类别的活性水平。与我们之前的观察结果（德特克，S.和保尔，M.R.（1975年）《生物化学与生物物理学报》383卷，67 - 77页）相反，即包囊形成过程中细胞核内对α - 鹅膏蕈碱敏感的聚合酶（II + III）的量增加，我们发现从全细胞中溶解出来的聚合酶II和III的量保持恒定。然而，聚合酶I的活性水平在细胞核和全细胞提取物中均保持恒定。因此，包囊形成过程中发生的核糖体RNA合成的关闭并非由于细胞中聚合酶I分子数量的减少。
