Which statement best describes the role of transcription cofactors?

• A. They bind DNA at promoters and enhancers.
• B. They are the primary RNA polymerase subunits.
• C. They modify chromatin structure and assist in assembling transcriptional machinery.
• D. They degrade histones during transcription.

Answer: (C)

Transcription cofactors mainly modify chromatin and help bring together the components needed for transcription. They usually don’t bind DNA directly; instead they interact with transcription factors bound to promoters or enhancers and recruit histone-modifying enzymes or chromatin-remodeling complexes, making the DNA more accessible. They also assist in assembling the transcriptional machinery by coordinating the recruitment of Mediator, general transcription factors, and RNA polymerase II. This is distinct from RNA polymerase subunits themselves, which are the core enzymatic components, and from DNA-binding transcription factors, which recognize specific DNA sequences. Degrading histones isn’t a typical role of transcription cofactors. So the statement that best describes their role is that they modify chromatin structure and assist in assembling transcriptional machinery.