Mediator (coactivator)

Mediator is a multiprotein complex that functions as a transcriptional coactivator. It was discovered by Roger D. Kornberg, winner of the 2006 Nobel Prize in Chemistry. It is also referred to in scientific literature as the Vitamin D Receptor Interacting Protein (DRIP) coactivator complex and the Thyroid Hormone Receptor-associated Proteins (TRAP).

The Mediator complex is required for the successful transcription of nearly all class II gene promoters in yeast. It works in the same manner in mammals. The mediator functions as a coactivator and binds to the C-terminal domain of RNA polymerase II holoenzyme, acting as a bridge between this enzyme and transcription factors.