In the context of DNA or genetics, the promoter is the part of the gene, 5' direction of the coding region, that is responsible for controlling how the gene get's turned on.

It does this by having the DNA sequence that binds to proteins that initiate DNA transcription (which is the process by which an RNA copy of DNA is made. This is a prerequisite for making the protein). The nature of the promoter determines how and what kind of transcriptional proteins bind to it.

Some promoters are always active, like those from certain viruses. Others are under exquisite control, like the promoter for beta-galactosidase of E. coli, which is only active when lactose is present.

The whole control circuitry is sometimes called the operon. The beta-galactosidase control element is called the lac operon. François Jacob and Jacques Monod first fully described the lac operon. This was a key discovery in modern biology. Them and André Lwoff won the 1965 Nobel Prize for Medicine for the discovery.

Pro*mot"er (?), n.


One who, or that which, forwards, advances, or promotes; an encourager; as, a promoter of charity or philosophy.



Specifically, one who sets on foot, and takes the preliminary steps in, a scheme for the organization of a corporation, a joint-stock company, or the like.


One who excites; as, a promoter of sedition.


An informer; a makebate.




© Webster 1913.

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