What do activator proteins recruit to initiate transcription after chromatin modification?

To initiate transcription after chromatin modification, activator proteins play a crucial role by recruiting RNA Polymerase II to the promoter region of the gene. When chromatin undergoes modifications, such as acetylation or methylation, these changes alter the accessibility of DNA. Activator proteins bind to specific enhancer sequences in this accessible chromatin, facilitating the recruitment of RNA Polymerase II, which is essential for synthesizing RNA from the DNA template. This process is a critical step in the transcription initiation complex, ensuring that transcription is not only initiated but also regulated effectively.

Ribosomes are involved in translation, not transcription, while transcription factors can help in forming the pre-initiation complex but are not the primary target of activator proteins in this context. Introns are segments of a gene that are removed during RNA processing and are not directly involved in the recruitment process for transcription initiation.