| Types | DnaRegion
|
| Roles | Regulatory
promoter
|
Description
The promoter has three operator sites named (sequentially) OR1, OR2, OR3. When the gene under the promoter is expressed, its product binds first to site OR1 on the promoter. This ensures (induces) transcription at normal rate. As the gene-product concentration increases, the product also binds to the site OR2 (along with OR1) to enhance the gene transcription (by even a factor of 11 times, according to literature). At very large concentrations of gene product, it now binds to OR3, which causes repression of transcription. Thus concentration of gene product is maintained.
Notes
none
Source
The promoter comes from the DNA sequence of Lambda phage.
