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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.
Additionally, adding methyl groups to the SHP-1 gene (which reduces the amount of SHP-1 produced) has been linked to lymphoma (a type of blood cancer) . [43] However, SHP-1 may also promote JAK-STAT signalling. A study in 1997 found that SHP-1 potentially allows higher amounts of STAT activation, as opposed to reducing STAT activity. [44]
Activator protein 1 (AP-1) is a transcription factor that regulates gene expression in response to a variety of stimuli, including cytokines, growth factors, stress, and bacterial and viral infections. [1] AP-1 controls a number of cellular processes including differentiation, proliferation, and apoptosis. [2]
Gal4 is a modular protein consisting broadly of a DNA-binding domain and an activation domain. The UAS to which GAL4 binds is CGG-N 11-CCG, where N can be any base. [6] Although GAL4 is a yeast protein not normally present in other organisms it has been shown to work as a transcription activator in a variety of organisms such as Drosophila, [7] and human cells, highlighting that the same ...
Thus, acetylation of histones is known to increase the expression of genes through transcription activation. Deacetylation performed by HDAC molecules has the opposite effect. By deacetylating the histone tails, the DNA becomes more tightly wrapped around the histone cores, making it harder for transcription factors to bind to the DNA.
Activator binds to an inducer and the complex binds to the activation sequence and activates target gene. [2] Removing the inducer stops transcription. [2] Because a small inducer molecule is required, the increased expression of the target gene is called induction. [2] The lactose operon is one example of an inducible system. [2]
The difference in brain size between humans and apes, for instance, has been linked to mutations in the gene Asb11, which is an upstream activator of SOX2 in the developing neural system. [ 20 ] Induced pluripotency is possible using adult neural stem cells, which express higher levels of Sox2 and c-Myc than embryonic stem cells.
It is required for the successful transcription of nearly all class II gene promoters in yeast. [7] It works in the same manner in mammals. The mediator functions as a coactivator and binds to the C-terminal domain of RNA polymerase II holoenzyme , acting as a bridge between this enzyme and transcription factors .