Which statement about enhancers is true?

Which statement about enhancers is true?

• A. Enhancers must be located immediately upstream of the promoter and always in the same orientation.
• B. Enhancers can function at a distance from the promoter, upstream or downstream, and operate in an orientation-independent manner.
• C. Enhancers recruit RNA polymerase II directly to the coding region.
• D. Enhancers are the protein products that bind to promoter to initiate transcription.

Answer: (B)

Enhancers are regulatory DNA elements that can boost transcription from a promoter even when they are far away, and they work in an orientation-independent manner. They achieve this through looping of the DNA, which brings the enhancer-bound transcription factors into contact with the promoter and the transcriptional machinery, facilitating initiation. They can be located upstream or downstream of the gene, even within introns, and moving them around or flipping their orientation does not necessarily abolish their activity. Importantly, enhancers do not recruit RNA polymerase II directly to the coding region, and they are not proteins themselves. They function by binding transcription factors and coactivators, which help recruit the general transcription factors and RNA Pol II to the promoter through the mediator complex and other looping interactions.

Enhancers are regulatory DNA elements that can boost transcription from a promoter even when they are far away, and they work in an orientation-independent manner. They achieve this through looping of the DNA, which brings the enhancer-bound transcription factors into contact with the promoter and the transcriptional machinery, facilitating initiation. They can be located upstream or downstream of the gene, even within introns, and moving them around or flipping their orientation does not necessarily abolish their activity.

Importantly, enhancers do not recruit RNA polymerase II directly to the coding region, and they are not proteins themselves. They function by binding transcription factors and coactivators, which help recruit the general transcription factors and RNA Pol II to the promoter through the mediator complex and other looping interactions.