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In prokaryotes, the term corepressor is used to denote the activating ligand of a repressor protein. For example, the E. coli tryptophan repressor (TrpR) is only able to bind to DNA and repress transcription of the trp operon when its corepressor tryptophan is bound to it.
coactivator – a protein (or a small molecule) that works with transcription factors to increase the rate of gene transcription; corepressor – a protein (or a small molecule) that works with transcription factors to decrease the rate of gene transcription; response element – a specific sequence of DNA that a transcription factor binds to
A repressor that binds with a co-repressor is termed an aporepressor or inactive repressor. One type of aporepressor is the trp repressor , an important metabolic protein in bacteria. The above mechanism of repression is a type of a feedback mechanism because it only allows transcription to occur if a certain condition is present: the presence ...
The repressor gene, lacI, will produce the repressor protein LacI which is under allosteric regulation. These genes are activated by the presence of lactose in the cell which acts as an effector molecule that binds to LacI. When the repressor is bound to lactose, it will not bind to the operator, which allows RNA polymerase to bind to the ...
Tryptophan repressor (or trp repressor) is a transcription factor involved in controlling amino acid metabolism. It has been best studied in Escherichia coli , where it is a dimeric protein that regulates transcription of the 5 genes in the tryptophan operon . [ 1 ]
The ability of nuclear receptors to alternate between activation and repression in response to specific molecular cues, is now known to be attributable in large part to a diverse group of cellular factors, collectively termed coregulators and including coactivators and corepressors.
The use of activation and coactivation allows for greater control over when, where and how much of a protein is produced. [ 1 ] [ 7 ] [ 16 ] This enables each cell to be able to quickly respond to environmental or physiological changes and helps to mitigate any damage that may occur if it were otherwise unregulated.
corepressor – a protein that works with transcription factors to decrease the rate of gene transcription In molecular biology and genetics , transcriptional regulation is the means by which a cell regulates the conversion of DNA to RNA ( transcription ), thereby orchestrating gene activity .