Mediator

Mediator itself is a large complex consisting of approximately 22 polypeptides. This large structure is formed from 3 domains: the head, middle and tail which as unit can either exist on its own or associated with RNA polymerase II via the c-terminal domain.

Function

The main function of the mediator complex is to interact with activators. These mediator-activator interactions, along with other transcription factors, aid the recruitment and assembly of the pre-initiation complex (PIC).