Primary information about promoters

Eukaryotic promoters

To turn a gene into a protein product, at least two general steps are required:

1. the gene is transcribed, spliced and processed to form mRNA, and
2. the mRNA is translated into a polypeptide.

Transcription is a controlled process. While multiple DNA regions are involved, the promoter is the main determinant for the initiation of transcription and modulation of levels and timing of gene expression.

Promoters in eukaryotic organisms- e.g. plants, animals- comprise multiple elements, some of which are found in nearly all promoters. These include:

• CAAT box. A consensus sequence close to -80 bp from the start point (+1). It plays an important role in promoter efficiency, by increasing its strength, and it seems to function in either orientation. This box is replaced in plants by a consensus sequence called the AGGA box;
• TATA box. A sequence usually located around 25 bp upstream of the start point. The TATA box tends to be surrounded by GC rich sequences. The TATA box binds RNA polymerase II and a series of transcription factors (TFIIX, X being a letter that identifies an individual transcription factor) to form an initiation complex;
• GC box. A sequence rich in guanidine (G) and cytidine (C) nucleotides, is usually found in multiple copies in the promoter region, normally surrounding the TATA box; and
• CAP site. A transcription initiation sequence or start point defined as +1, at which the transcription process actually starts.

RNA polymerase II is the enzyme that transcribes a gene into RNA. It works in conjunction with other transcription factors that recognize signals embodied in the promoter region. RNA polymerase II starts its "journey" at the TATA region where it binds and travels along the DNA until it reaches the CAP site where the actual synthesis of RNA starts. The transcription process only takes place in the downstream direction, from 5' (left) to 3' (right).

These elements are normally regarded as constituents of the promoter region itself, but depending on the scope of definition of a promoter in a patent or patent application, and whether the definition is expressed in functional or structural terms, other elements may be included as part of a promoter region.

Enhancers, for example, are elements located at variable distances from the promoter "itself" and contain several closely arranged sequence elements that bind to transcription factors. These elements enhance the activity of a promoter and are orientation-independent with respect to the promoter and can be upstream or downstream of a promoter (e.g., such as within intron sequences of a gene). There is currently a high interest in studying and isolating enhancers, which can be successfully attached to heterologous promoter regions to increase transcriptional activity and in some cases to provide additional levels of control (e.g., to confer tissue-specific or stage-specific expression of a gene).

The information contained in this page was believed to be correct at the time it was collated. New patents and patent applications, altered status of patents, and case law may have resulted in changes in the landscape. CAMBIA makes no warranty that it is correct or up to date at this time and accepts no liability for any use that might be made of it. Corrections or updates to the information are welcome. Please send an email to info@bios.net.

CAMBIA Login