Final answer:
Mediator regulates the strength of transcription through contacts made with transactivators and the phosphorylation state conferred by TFIIH.
Step-by-step explanation:
The proposed mechanism for how Mediator regulates the strength of transcription is based on different conformational states. These states provide different degrees of efficiency for the re-entry of RNA polymerase II (pol II) into the preinitiation complex (PIC) during reinitiation. One of the key factors that influences the amplitude of transcription is the phosphorylation state conferred by TFIIH, a complex involved in transcription initiation. When TFIIH phosphorylates pol II, it affects the efficiency of re-entry into the PIC, ultimately regulating the strength of transcription.
Another factor that can influence transcription strength is the contacts made by transactivators with the Mediator complex. Transactivators are proteins that enhance the activity of transcription factors. When transactivators bind to enhancer elements in the DNA, they recruit Mediator, which acts as a bridge between the enhancer-bound transactivators and the PIC. This interaction between Mediator and transactivators can modulate the amplitude of transcription.
In summary, Mediator can regulate the amplitude of transcription through different mechanisms, including contacts made with transactivators and the phosphorylation state conferred by TFIIH.