Activator (genetics)

An activator in genetics is a DNA -binding substance, such as low molecular weight or arabinose regulatory proteins that bind to the operator binding site in 3 'direction in front of the operator and thus the affinity of the RNA polymerase to the promoter increases, whereby the transcription of the gene (or operon ) is activated. The activator is activated by a co-activator ( signal substance ), or inductor.

A distinction between constitutive and regulated activators.

Example

• Catabolite repression: The activator CAP ( catabolite activator protein), is activated in the presence of the coactivator cAMP, the transcription of the lactose operon ( lac operon ).