Importantly, mediator and transcription factors do not dissociate from the DNA at the time polymerase begins transcription. Rather, the complex remains at the promoter to recruit another RNA polymerase to begin another round of transcription.How does medmediator interact with RNA polymerase?
Mediator has been shown to make contacts with the polymerase in the transcription preinitiation complex. A recent model showing the association of the polymerase with mediator in the absence of DNA is shown in the figure to the left. In addition to RNA polymerase II, mediator must also associate with transcription factors and DNA.Do mediators form stable associations with non-coding RNA?
There is a report that mediator forms stable associations with a particular type of non-coding RNA, ncRNA-a. These stable associations have also been shown to regulate gene expression in vivo, and are prevented by mutations in MED12 that produce the human disease FG syndrome.What is the role of mediator in the formation of heterochromatin?
In addition to the looping of euchromatin, mediator appears to be involved in formation or maintenance of heterochromatin at centromeres and telomeres. TGFβ signaling at the cell membrane results in 2 different intracellular pathways. One of them depends on MED15, while the other is independent of MED15.