真核生物Ⅱ类基因的转录起始

Transcription Initiation of Eukaryotic Class Ⅱ Genes

真核生物Ⅱ类基因的转录起始是一个非常复杂并且受到严格调控的过程 .它涉及到染色体结构的改变、顺式作用元件和反式作用因子相互作用等多种过程 .关于Ⅱ类基因基础转录起始复合物在启动子区的装配的研究 ,目前存在两种模型 ,即分步组装模型与RNAPⅡ全酶模型 ,它们分别是基于体外重建转录实验的结果以及酵母中RNAPⅡ全酶巨酶体系的发现而提出的 .在转录激活的分子机制上目前认为存在两个相互联系的过程 ,即解抑制作用和真正的激活作用 .

The transcription initiation of eukaryotic class Ⅱ genes is very complicated and strictly regulated. Many events such as the alteration of chromatin structure, the interaction between cis-elements and trans-factors are involved in this process. Based on the results of in vitro reconstitution transcription and the discovery of RNAPⅡ holoenzyme in yeast respectively, two models, step-wise assembly model and RNAPⅡ holoenzyme model, were proposed on the assembly of basal transcription initiation complex at promoters. Two related processes, antirepression and true activation, were supposed to be the molecular mechanism of the transcriptional activation.