Response elements are a class of cis-acting elements, and are the recognition sites of certain transcription factors. Response elements are sequence modules that coordinate the regulation of genes and ensure that different genes are expressed in a coordinated fashion or simultaneously.
Features of response elements:
1. can be located in a promoter or an enhancer sequence
2. have no fixed location, rather they are usually within 200 bp upstream of the transcription start site (most are located within 1 kb of the tss).
3. a single element is usually sufficient to confer a regulatory response
4. contain short consensus sequences
5. modules are related but not identical
6. it is assumed that a specific protein factor (trans-acting) binds to the element, and that the presence of that protein is developmentally regulated
For example, the cAMP response element (CRE) interacts with the transcription factor CREB (CRE-binding protein), which is regulated by cAMP. The consensus sequence for CRE is TGACGTCA.
Receptors for steroid hormones act as transcription factors for hormone response elements, such as ERE, GRE, TRE & T3RE
ERE : GRE : HSE : SRE : TRE : T3RE
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In general, a consensus sequence is that idealized sequence in which each position represents the base/amino acid most often found when many sequences are compared. A genetic consensus sequence is a sequence of nucleotides that is common to different genes or genomes. There may be some variations but such sequences show considerable similarity. So, a consensus sequence is the prototype sequence that most others approach.
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