Repressor

In molecular genetics, a repressor is a DNA-binding protein that regulates the expression of one or more genes by binding to the operator and blocking the attachment of RNA polymerase to the promoter, thus preventing transcription of the genes. This blocking of expression is called repression.

Repressor proteins are coded for by regulator genes. Repressor proteins then attach to a DNA segment known as the operator. By binding to the operator, the repressor protein prevents the RNA polymerase from creating messenger RNA.

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Other articles related to "repressor":

Trp Operon - Repression
... The repressor for the trp operon is produced upstream by the trpR gene, which is continually expressed at a low level ... When tryptophan is present, these tryptophan repressor tetramers bind to tryptophan, causing a change in conformation (in the repressor), which allows the repressor to bind the operator ... When tryptophan is not present, the repressor is in its inactive conformation and cannot bind the operator region, so transcription is not inhibited by the repressor ...
Lac Operon - Regulation - Multimeric Nature of The Repressor
... The lac repressor is a tetramer of identical subunits ... The operator site where repressor binds is a DNA sequence with inverted repeat symmetry ... half-sites of the operator together bind to two of the subunits of the tetrameric repressor ...
Allolactose
... It binds to a subunit of the tetrameric lac repressor, which results in conformational changes and reduces the binding affinity of the lac repressor to the lac operator, thereby ... The absence of the repressor allows the transcription of the lac operon to proceed ...
Repressor - Examples - met Operon
... An example of a repressor protein is the methionine repressor MetJ ... When SAM concentration becomes low the repressor dissociates from the operator site allowing more methionine to be produced ...
MSin3 Interaction Domain
... domain (SID) is an interaction domain which is present on several transcriptional repressor proteins including TGFβ (transforming growth factor ... the paired amphipathic alpha-helix 2 (PAH2) domain of mSin3, a transcriptional repressor domain that is attached to transcription repressor proteins such as the mSin3A corepressor ...