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In genetics, a promoter is a sequence of DNA to which proteins bind to initiate transcription of a single RNA transcript from the DNA downstream of the promoter.
An active enhancer regulatory sequence of DNA is enabled to interact with the promoter DNA regulatory sequence of its target gene by formation of a chromosome loop. This can initiate messenger RNA (mRNA) synthesis by RNA polymerase II (RNAP II) bound to the promoter at the transcription start site of the gene. The loop is stabilized by one ...
Promoter activity of the P-RM and P-R promoters vs RNA polymerase concentration in the enterobacteriophage lambda [1]. Promoter activity is a term that encompasses several meanings around the process of gene expression from regulatory sequences —promoters [2] and enhancers. [3]
Gene expression in mammals is regulated by many cis-regulatory elements, including core promoters and promoter-proximal elements that are located near the transcription start sites of genes. Core promoters are sufficient to direct transcription initiation, but generally have low basal activity. [29]
Activator-binding sites may be located very close to the promoter or numerous base pairs away. [2] [3] If the regulatory sequence is located far away, the DNA will loop over itself (DNA looping) in order for the bound activator to interact with the transcription machinery at the promoter site. [2] [3]
The Pribnow box has a function similar to the TATA box that occurs in promoters in eukaryotes and archaea: it is recognized and bound by a subunit of RNA polymerase during initiation of transcription. [3] This region of the DNA is also the first place where base pairs separate during prokaryotic transcription to allow access to the template strand.
A transcription factor is a protein that binds to specific DNA sequences (enhancer or promoter), either alone or with other proteins in a complex, to control the rate of transcription of genetic information from DNA to messenger RNA by promoting (serving as an activator) or blocking (serving as a repressor) the recruitment of RNA polymerase.
In eukaryotes, the 5′ flanking region has a complex set of regulatory elements such as enhancers, silencers, and promoters. The primary promoter element in eukaryotes is the TATA box. Other promoter elements found in eukaryotic 5′ flanking regions include initiator elements, downstream core promoter element, CAAT box, and the GC box. [1]