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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. The RNA transcript may encode a protein ( mRNA ), or can have a function in and of itself, such as tRNA or rRNA .
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]
The promoter region is a prime regulator of transcription. Promoter regions regulate transcription of all genes within bacteria. As a result of their involvement, the sequence of base pairs within the promoter region is significant; the more similar the promoter region is to the consensus sequence, the tighter RNA polymerase will be able to bind.
Transcription preinitiation complex, represented by the central cluster of proteins, causes RNA polymerase to bind to target DNA site. The PIC is able to bind both the promoter sequence near the gene to be transcribed and an enhancer sequence in a different part of the genome, allowing enhancer sequences to regulate a gene distant from it.
An active enhancer regulatory region of DNA is enabled to interact with the promoter DNA region of its target gene by the 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 architectural ...
[c] For example, after binding the enhancer and core promoter, the mediator complex undergoes a compositional change in which the kinase module dissociates from the complex to allow association with RNA polymerase II and transcriptional activation. [6] The Mediator complex is located within the cell nucleus.
The tac promoter finds various applications. The tac promoter/operator (dubbed PTAC) is one of the most widely used expression systems. Ptac is a strong hybrid promoter composed of the –35 region of the trp promoter and the –10 region of the lacUV5 promoter/operator. The expression of PTAC is repressed by the lacI protein.
Further research at the late stage of thymocyte development reveals that distal Lck promoter with driven Cre will result in the distal lck gene promoter to drive Cre expression to be limited within innate-like T cells. There is a cell type specific function in innate-like T cells based on the distal lck promoter - driven Cre. [3]