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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.
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]
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]
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 ]
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 ...
upregulation, activation, or promotion – increase the rate of gene transcription downregulation , repression , or suppression – decrease the rate of gene transcription coactivator – a protein (or a small molecule) that works with transcription factors to increase the rate of gene transcription
Promoter - commonly used inducible promoters are promoters derived from lac operon and the T7 promoter. Other strong promoters used include Trp promoter and Tac-Promoter, which are a hybrid of both the Trp and Lac Operon promoters. Ribosome binding site (RBS) - follows the promoter, and promotes efficient translation of the protein of interest.
In biotechnology applications, T7 RNA polymerase is commonly used to transcribe DNA that has been cloned into vectors that have two (different) phage promoters (e.g., T7 and T3, or T7 and SP6) in opposite orientation. RNA can be selectively synthesized from either strand of the insert DNA with the different polymerases.