Gray W M, Fassler J S
Department of Biological Sciences, University of Iowa, Iowa City.
Gene Expr. 1993;3(3):237-51.
Binding sites for the transcription factor Rap1 are widespread in the yeast genome. With respect to many, but not all, genes, Rap1p has an apparent activation function. Whether Rap1 is itself a transcriptional activator, or whether it is in some way required for activation by additional factors, is not clear. We have identified a previously unrecognized Rap1p binding site in the internal regulatory region of Ty1 elements. We demonstrate that this site is capable of binding Rap1 in vitro and that, in vivo, Rap1p plays an important regulatory role in Ty1 and Ty1-mediated adjacent gene expression. Our data suggest that in Ty1 elements, maximal levels of RAP1-mediated activation depend on the formation of a complex with Mcm1, an independent DNA-binding protein that functions in transcription as well as in DNA replication, and with a third factor, IBF, previously identified as a binding activity with a site situated between the Rap1p and Mcm1p binding sites in this region of Ty1 elements.
转录因子Rap1的结合位点在酵母基因组中广泛存在。对于许多（但不是所有）基因而言，Rap1p具有明显的激活功能。Rap1本身是否是转录激活因子，或者它是否以某种方式是其他因子激活所必需的，目前尚不清楚。我们在Ty1元件的内部调控区域中鉴定出了一个先前未被识别的Rap1p结合位点。我们证明该位点在体外能够结合Rap1，并且在体内，Rap1p在Ty1以及Ty1介导的相邻基因表达中发挥重要的调控作用。我们的数据表明，在Ty1元件中，RAP1介导的激活的最大水平取决于与Mcm1形成复合物，Mcm1是一种独立的DNA结合蛋白，在转录以及DNA复制中发挥作用，还取决于与第三种因子IBF形成复合物，IBF先前被鉴定为在Ty1元件该区域的Rap1p和Mcm1p结合位点之间具有结合活性的一种因子。
