16.3.4—Transcription factors in eukaryotes

Transcription factors are proteins that bind specific regulatory DNA sequences and influence RNA-polymerase recruitment or activity. Activators increase transcription; repressors reduce it, often through interactions with other proteins and chromatin.

Multiple factors allow a eukaryotic cell to combine developmental, hormonal and environmental signals. The same gene can therefore be active in one tissue and silent in another.

A hormone-bound receptor can enter the nucleus, bind a response element and recruit co-activators, increasing transcription of a target gene.

A transcription factor does not necessarily bind the promoter itself. Enhancers, silencers, chromatin state and cofactors can all affect the final outcome.