Enhancers and promoters are different, but both play vital roles in DNA transcription. An enhancer is a special sequence of DNA that helps to increase the rate of initiation of DNA transcription by RNA polymerase II. Enhancers have specialized DNA called “response elements” that bind to transcription factors. Enhancers are always located on the same chromosome as the gene that is to be transcribed.
They can either be upstream or downstream of the transcription start site. On the other hand, the promoter is a special sequence of DNA that helps to initiate gene transcription by RNA polymerase II. In Eukaryotes, the promoter is made up of a sequence known as the TATA box, which is about 25 to 35 base pairs. It is always located upstream to the site of initiation. Unlike enhancers, promoters bind to both transcription factors and RNA polymerase II to initiation transcription.
An enhancer is a piece of a short DNA sequence that works on speeding up or enhancing the rate of the transcription of the genes. It is usually located either upstream or downstream of a specific gene that can be either a different or same orientation with the gene that it will transcribe. It does not need to be near at the initiation site to function as it can work on the transcribing the gene from a distance.
Enhancers are present in prokaryotic and eukaryotic cells and can also be found on intro and exons. The promoter, on the other hand, is a piece of a DNA sequence that indicates where the transcription will start. Unlike enhancers that can be found either in the upstream or downstream, promoters can be located in the upstream where transcription starts.
Enhancers and promoters are associated with genes. If you are near the transcriptional start site, then you will probably find the promoter. However, genes have enhancers throughout them. With the gene expression, enhancers will enhance them. That is why they are named the enhancers. Promoters, on the other hand, will start the gene expression, which is why it is named the promoters.
The effect of the positions of the enhancers and promoters are different. The enhancers position is independent, whereas the position of the promoter is dependent. Promoters conduct their work in the same transcriptional orientation, but the enhancer can work in the same or opposite orientation. It will work either way. Both the enhance and the promoter can be defined as specific sequences in DNA.