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A promoter is induced in response to changes in abundance or conformation of regulatory proteins in a cell, which enable activating transcription factors to recruit RNA polymerase. [4] [5] Given the short sequences of most promoter elements, promoters can rapidly evolve from random sequences.
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 has been commonly characterized as a measure of how much, how fast, when and where this process happens. [ 4 ]
The promoters used for these vector are usually based on the promoter of the lac operon or the T7 promoter, [11] and they are normally regulated by the lac operator. These promoters may also be hybrids of different promoters, for example, the Tac-Promoter is a hybrid of trp and lac promoters. [12]
The CAG promoter is a strong synthetic promoter frequently used to drive high levels of gene expression in mammalian expression vectors. [1] [2] CAG promoter was constructed in the lab of Dr Jun-ichi Miyazaki [3] [4] from the following sequences: (C) the cytomegalovirus (CMV) early enhancer element,
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]
A sigma factor is a protein needed only for initiation of RNA synthesis in bacteria. [12] Sigma factors provide promoter recognition specificity to the RNA polymerase (RNAP) and contribute to DNA strand separation, then dissociating from the RNA polymerase core enzyme following transcription initiation. [13]
In molecular biology, a downstream promoter element (DPE) is a core promoter element. Like all core promoters, the DPE plays an important role in the initiation of gene transcription by RNA polymerase II. The DPE was first described by T. W. Burke and James T. Kadonaga in Drosophila melanogaster at the University of California, San Diego in ...
The tac promoter consists of the '–35' region of the trp promoter and the '–10' region of the lac promoter (and differs from a related trc promoter by 1 bp [3]). The tac promoter is, therefore, inducible by IPTG (Isopropyl β- D -1-thiogalactopyranoside), whilst also allowing higher maximum gene expression than either the lac or trp promoters.