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A transcriptional activator is a protein (transcription factor) that increases transcription of a gene or set of genes. [1] Activators are considered to have positive control over gene expression, as they function to promote gene transcription and, in some cases, are required for the transcription of genes to occur.
Although as early as 1951, Barbara McClintock showed interaction between two genetic loci, Activator (Ac) and Dissociator (Ds), in the color formation of maize seeds, the first discovery of a gene regulation system is widely considered to be the identification in 1961 of the lac operon, discovered by François Jacob and Jacques Monod, in which ...
Its discovery was based on studying its genetic behavior, i.e., "jumping genes" in maize and published by Barbara McClintock, [3] [4] leading to her 1983 Nobel Prize in Medicine. The Ac/Ds transposable elements were first isolated and sequenced By Fedoroff et al. 1983 [5] using insertions of Ac and Ds into the well-studied Waxy(Wx1) gene.
Illustration of an activator. In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence.
Examining which sgRNAs yield a phenotype suggests which genes are involved in a specific pathway. The dCas9 activation system can be used to control exactly which cells are activated and at what time activation occurs. dCas9 constructs have been made that turn on a dCas9-activator fusion protein in the presence of light or chemicals.
If the repressor has a higher affinity for its motif than the activator, transcription would be effectively blocked in the presence of the repressor. Tight regulatory control is achieved by the highly dynamic nature of transcription factors. Again, many different mechanisms exist to control whether a transcription factor is active.
Tetracycline-controlled transcriptional activation is a method of inducible gene expression where transcription is reversibly turned on or off in the presence of the antibiotic tetracycline or one of its derivatives (e.g. doxycycline).
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. [1] [7]