What are regulatory sequences on DNA that increase the rate of transcription when activator proteins bind to them called?

Regulatory sequences on DNA that increase the rate of transcription when activator proteins bind to them are known as enhancers. Enhancers are specific regions that can be located far from the promoter they regulate, and they function by providing binding sites for activator proteins. When these proteins attach to the enhancer, they can loop the DNA to interact with the transcription machinery at the promoter region, facilitating a more efficient initiation of transcription.

This process is crucial in gene regulation, as enhancers can significantly amplify the expression of specific genes in response to various signals, thus allowing for a finely tuned control of gene activity during cellular processes such as development and response to environmental stimuli.