Coactivators and corepressors are transcription factors that do not bind to DNA (Excerpt from Pages 83–84)
Some transcription factors that are required for the activation of gene transcription do not directly bind to DNA. These proteins are called coactivators. Coactivators work in concert with DNA-binding transcriptional activators to stimulate gene transcription. They function as adapters or protein intermediaries that form protein-protein interactions between activators bound to enhancers and the basal transcriptional machinery assembled on the gene promoter. Coactivators often contain distinct domains, one that interacts with the transactivation domain of an activator and a second that interacts with components of the basal transcriptional machinery. Transcription factors that interact with repressors and play an analogous role in transcriptional repression are called corepressors.