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The SOS response is a global response to DNA damage in which the cell cycle is arrested and DNA repair and mutagenesis are induced. The system involves the RecA protein (Rad51 in eukaryotes). The RecA protein, stimulated by single-stranded DNA, is involved in the inactivation of the repressor of SOS response genes thereby inducing the response ...
Checkpoint-control proteins that trigger cell cycle arrest in response to DNA damage or chromosomal defects (e.g., breast cancer type 1 susceptibility protein (BRCA1), p16, and p14). [15] Proteins that induce apoptosis. If damage cannot be repaired, the cell initiates programmed cell death to remove the threat it poses to the organism as a whole.
That mRNA is then translated into proteins. When a repressor protein binds to the silencer region of DNA, RNA polymerase is prevented from transcribing the DNA sequence into RNA. With transcription blocked, the translation of RNA into proteins is impossible. Thus, silencers prevent genes from being expressed as proteins. [1]
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 dimerization domain binds to other LexA polypeptides to form dumbbell shaped dimers. The DNA-binding domain is a variant form of the helix-turn-helix DNA binding motif, [4] and is usually located at the N-terminus of the protein. [1] This domain is bound to an SOS box upstream of SOS response genes until DNA damage stimulates ...
Repressor proteins bind to the DNA strand and prevent RNA polymerase from being able to attach to the DNA and synthesize mRNA. Inducers bind to repressors, causing them to change shape and preventing them from binding to DNA. Therefore, they allow transcription, and thus gene expression, to take place.
The 3'-UTR also may have silencer regions that bind repressor proteins that inhibit the expression of an mRNA. [citation needed] The 3'-UTR often contains microRNA response elements (MREs). MREs are sequences to which miRNAs bind and cause gene silencing. These are prevalent motifs within 3'-UTRs.
RE1-Silencing Transcription factor (REST), also known as Neuron-Restrictive Silencer Factor (NRSF), is a protein which in humans is encoded by the REST gene, and acts as a transcriptional repressor. [ 5 ] [ 6 ] [ 7 ] REST is expressly involved in the repression of neural genes in non-neuronal cells.