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I have been confused as to the difference between a response element and an enhancer.

Wikipedia has the definition of response element as the following:

Response elements are short sequences of DNA within a gene promoter region that are able to bind specific transcription factors and regulate transcription of genes.

Wikipedia's definition of enhancers:

In genetics, an enhancer is a short (50-1500 bp) region of DNA that can be bound by proteins (activators) to increase the likelihood that transcription of a particular gene will occur.[1][2] These proteins are usually referred to as transcription factors.

They seem almost the same. What are the main differences?

The only difference I can see is that response elements can both halt transcription or allow for it. While enhancers only promote transcription if the transcription factor is present.

Is this the difference between the two, or is there something else that differentiates them?

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Enhancers specifically bind transcription factors in an effort to obtain robust rates of transcription, in a very general fashion and may be upstream or downstream of a promoter. Remember that you don't need to receive a signal to produce housekeeping genes, regulated by general transcription factors, because they're always needed (in part). A response element can enhance or repress transcription depending on the stimulus.

Vitamin D response element (VDRE) is a fair example: In response to your extracellular calcitriol or 1,25(OH)2D, the vitamin D receptor will complex with a number of proteins that bind at the VDRE, controlling transcription of various vitamin D-controlled gene targets.

Vitamin D activity is mediated through binding of 1,25(OH)2D3 to the vitamin D receptor (VDR), which can regulate transcription of other genes involved in cell regulation, growth, and immunity. VDR modulates the expression of genes by forming a heterodimer complex with retinoid-X-receptors (RXR).

Source: http://www.wikipathways.org/index.php/Pathway:WP1531

And just as well, other promoters such as that for pro-parathyroid hormone contain VDRE sequences that suppress it's transcription (ref).

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  • $\begingroup$ I had the notion that transcription factors binding to enhancers can also have a ligand binding domain. Which would mean that it would be activating depending on a stimulus. If my notion is correct, what then differentiates them? $\endgroup$
    – Hawkeye
    Commented Aug 8, 2017 at 20:53
  • $\begingroup$ Essentially your RE is always in the promoter, and the action can be bidirectional, either activating or silencing, based on the same stimulus across genes that contain that RE. You enhancer can be anywhere and always up-regulates in response to any number of variables that site reacts to. $\endgroup$
    – CKM
    Commented Aug 8, 2017 at 21:09
  • $\begingroup$ You know it just cant be miles away from the TSS because it still needs to interact, so when I say anywhere I mean not just in the promoter. $\endgroup$
    – CKM
    Commented Aug 8, 2017 at 21:13
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A response element is a DNA sequence that binds with a set of one or more transcription factors/cofactors/factors in order to regulate transcription. A response element is usually specific to a given stimulus that a cell needs to respond to.

A promoter is a sequence of DNA located nearby a gene and contains one or multiple response elements and up-regulates transcription

Once a promoter’s response element is binding with factors and is beginning to be set up for its role in transcriptional up-regulation of the nearby gene, the response element of another, second sequence of DNA (typically farther away from the gene than the promoter) has its own response element that in turn begins to bind with its own factors.

The factors of this other, second sequence interact directly or indirectly with the promoter’s factors to enhance the promoter’s transcriptional up-regulation to the gene. This other, second sequence is called an enhancer.

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