Enhancer

Enhancer

An enhancer is a short region of DNA that can be bound by proteins (activators) to increase the likelihood that transcription of a particular gene will occur. These proteins are usually referred to as transcription factors.

Function

Enhancers can be located upstream or downstream of the gene they regulate, and can be located far away from the promoter region of the gene or even in an intron or in the gene they regulate. They do not act on the promoter region itself, but are bound by activator proteins. These proteins can then interact with the transcription machinery and promoter region through a protein-protein interaction, and thus help the RNA polymerase to bind to the promoter.

Mechanism

The enhancer region is first bound by proteins known as transcription factors. These factors have specific binding sites in the enhancer region. Once bound, they can interact with other proteins that are part of the transcription machinery, such as RNA polymerase and the general transcription factors, which can bind to the promoter. This interaction forms a loop in the DNA, bringing the enhancer region (and bound proteins) close to the promoter, which can then increase transcription of the gene.

Types of Enhancers

There are two types of enhancers based on their location relative to the gene they regulate:

• Proximal Enhancers - These are located close to the promoter of the gene they regulate.
• Distal Enhancers - These are located further away from the promoter of the gene they regulate.

See Also

• Promoter (genetics)
• Transcription (genetics)
• Transcription factor
• Gene expression

References

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