中介因子复合体在基因转录调控中的作用

Mediator Complexes in Gene Transcription

近二十年来 ,人类在不断探索基因转录调控的机制方面取得了长足的进步 ,其中包括对中介因子复合体 (mediatorcomplex)的克隆、鉴定及作用机制的研究。中介因子是由 2 0多种不同蛋白亚基组成的复合体 ,广泛存在于各种真核生物的细胞中 ,并且与RNA聚合酶一起构成RNA聚合酶II全酶。中介因子复合体可与转录因子和RNA聚合酶II相互作用 ,因而在基因转录过程中发挥着桥梁的作用。中介因子复合体不但能够促进基因转录的激活 ,有时也能抑制基因转录。本文总结了中介因子复合体的组成。

Major progresses have been made in recent years in understanding of the molecular mechanism involved in gene transcriptional regulation; these include the cloning and identification as well as functional analysis of mediator complexes. Mediator complexes, which consist of more than 20 protein subunits, have been found in a variety of eukaryotes including yeast, mouse and human. Mediators are capable of interacting with both transcription factors and RNA polymerase II, and thus are believed to participate in the transcription process by bridging specific transcription factors and the basal transcriptional machinery. The functional consequences of mediator complexes in gene regulation could be either positive or negative. This review is focused on recent findings regarding the composition, the structure and the function of mediator complexes.