What is the proximal promoter?
The proximal proximal promoter is the area in deoxyribonucleic acid (DNA) just before the start of the gene, where proteins and other molecules bind to reading this gene. The promoter area is essential for reading and rewriting into protein, both in simple prokaryotic cells and in more complex eukaryotes. Many proteins called transcription factors are bound to DNA in this area and perform many tasks preparing for gene transcription. The most important of these functions is building protein scaffolding, which holds DNA open and rewrites the right gene simultaneously.
The exact position and structure of the proximal promoter differ between genes and cell types. Prokaryotic cells, nucleus cells usually have one type of promoter, while eukaryotic cells, cells with real core, have another. Promotors usually lie several nucleotides upstream or previously the gene that controls. Almost every promoter contains special sequencence of nucleotides that identify them as such. BothThe prokaryotic promoters are identified by a group of nucleotides called Shine-Dalgarno sequence and eukaryotic promoters are identified by a specific genetic sequence called Tata Box.
Despite these relatively simple rules, not every proximal promoter follows, which can be difficult, and the genes they control are somewhat difficult. The distance between the promoter and its gene is not fixed within a species or within a single organism, so the determination where it sits in relation to themselves is not trivial. The proximal composition of the proximal promoter sequence is not always identical; They can very much in length, composition or both. In addition, marker sequences of Shine-Dalgarno or Tata Box have some variability. How a variety of transcription factors recognize promoters in the face of this own variabilitation easy to determine and new examples often appear that question these previously robustsolution.
When the gene is very close to another gene, there is a possibility that its proximal promoter could be influenced by the action of a nearby gene. Sometimes it is done deliberately in the genome, perhaps to stimulate multiple genes at the same time or regulate their action at the same time. At other times, it is associated with the mistake of the connection between two genes through the promoter activity. To avoid this crossing between genes, where it is not guaranteed, some genomes have the insulator areas among themselves. This extra area is not always necessary, and some genomes prevent cross -coil calls according to the location of genes in other ways, such as forcing one gene to be inactive while the other is active.