A transcriptional activator is a protein (transcription factor) that increases transcription of a gene or set of genes. Activators are considered to have positive control over gene expression, as they function to promote gene transcription and, in some cases, are required for the transcription of genes to occur.

What do transcription activators do?

Transcriptional activators are proteins that bind to DNA and stimulate transcription of nearby genes. Most activators enhance RNA polymerase binding (formation of the closed complex) or the transition to the open complex required for initiation of transcription.

How does transcriptional control work?

In molecular biology and genetics, transcriptional regulation is the means by which a cell regulates the conversion of DNA to RNA (transcription), thereby orchestrating gene activity. ... This control allows the cell or organism to respond to a variety of intra- and extracellular signals and thus mount a response.