Promoters are near the genes they transcribe. They are on the same strand of DNA and are 'upstream'.
Promoters contain specific DNA sequences which give the RNA polymerase a place to bind. Other proteins also help this to happen. Some can also stop it from happening. The whole thing is called "the regulation of gene expression".
- In bacteria
- The promoter is recognized by RNA polymerase and another protein.
- In eukaryotes
- The process is more complicated. At least seven different factors are needed so RNA polymerase II can bind to the promoter.
Promoters are important parts of the DNA. They work with other regulatory regions. Together, they adjust the level of transcription of a gene. So, genes get switched on when they are needed, and switched off when they are not. When they are on, they get adjusted up or down as needed.
- "Analysis of biological networks: transcriptional networks - promoter sequence analysis" (PDF). Tel Aviv University. Retrieved 30 December 2012.