Regulatory elements promoters

Each gene would need to have common regulatory elements, promoters, operators, or both, associated with it. In this way, a single control factor, such as a repressor or positively acting substance, could influence all genes simultaneously. 

Key Words Transcription factor binding site regulatory element promoter phylogenetic footprinting orthologous sequence alignment. 

The expression of the lacZ transgene varies according to the nature of the regulatory elements (promoter and enhancer) that drive gene expression, the... 

The gene promoter is a nucleotide sequence in DNA near the start of a gene, consisting of regulatory elements to which transcription factors and RNA polymerase bind. This leads to activation of the gene promoter and transcription of the corresponding gene. 

Regulatory regions are transcriptional control sequences, which consist of promoters, response elements, enhancers and possibly silencers, located upstream of the start site of transcription. The overall effect on gene transcription is a sum of the contributions of these elements and the activities of proteins recruited to these sites. Promoters are located immediately upstream of the start site and initiate transcription. They often contain tissue- or cell-specific elements if the gene is not ubiquitously expressed. Enhancers are positive regulatory elements which function independently of orientation and distance from the genes they regulate. 

Figure 4. Transcriptional regulatory sequences of the mouse c-mos gene. Transcription in oocytes and spermatocytes initiates 53 and approximately 280 base pairs upstream of the c-mos ATG, respectively. Efficient transcription in oocytes requires an initiator (Inr)-I ike sequence located downstream of the transcription start site. A negative regulatory element (NRE) located upstream of the spermatocyte promoter acts to suppress c-mos transcription in somatic cells.

Figure 6. The c-mos negative regulatory element (NRE). Nucleotide positions of the NRE are shown relative to the spermatocyte transcription start site, taken as 280 base pairs upstream of the c-mos ATG (see Fig. 4). The endpoints of the NRE are defined by deletions that allow c-mos expression in NIH 3T3 and other somatic cells. Mutations of the sequences designated by boxes 1,2, and 3 also allow c-mos transcription in NIH 3T3 cells, indicating that these sequences represent functional elements within the NRE. Boxes 1 and 2 are similar to sequences upstream of the protamine (Prot) promoter that inhibit in vitro transcription in HeLa cell extracts. A sequence just upstream of box 2 is also similar to a putative repressor-binding site in the regulatory region of Pgk2.

GanB, R., Schiitz, G., and Beermann, F. (1994a). The mouse tyrosinase gene promoter modulation by positive and negative regulatory elements. J. Biol. Chem. (in press). 

ADH6 was discovered by nucleotide cross-hybridization, and has not yet been demonstrated as a functional protein. The mRNA is found in liver (both adult and fetal) and stomach. ADH6 has a fully functional promoter, active in both hepatoma cells and fibroblasts [37]. There are several positive cis-acting elements in the proximal promoter, several of which are bound by C/EBP. There is a compound cell-specific regulatory element about 2 kb upstream, that is a positive element in the hepatoma cells and a negative element in fibroblasts [23]. 

Within each species, individual promoters resulted in distinct, tissue-dependent accumulation patterns. The cauliflower mosaic virus (CaMV) 35S promoter, for example, led to high-level accumulation in callus and leaves whereas the maize ubiqui-tin-1 promoter was the best choice for producing recombinant proteins in cereal seeds even though it is not in itself seed-specific [23]. The lack of such comparative studies for proteins other than rAbs makes it difficult to generalize an optimal expression strategy for all proteins. Tables 7.1 and 7.2 list recombinant proteins expressed in plants and provide details of the production system, promoters and other regulatory elements used in each case. 

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