Transcription and RNA Processing

ID #2407

once the whole RNA polyermase holoenzyme is assembled, the sigma factor finds the promoter region, then transcription is initiated. But is the sigma factor still connected to the RNA polymerase and the rest of the holoenzyme when it actually finds the promoter? For eukaryotes you talk about how the transcription factors do bind to the DNA. So then the RNA finds that the transcription factor is bound already to promoter and then joins the party, or do the transcription factors go out of their way to drag the RNA polymerase to the promoter? So does the RNA polymerase come to the transcription factors or do the transcription factors go to the RNA polymerase?

For your first question, yes, the sigma factor is still attached to the RNA Polymerase core enzyme when recognizing the promoter. Sigma factor will not separate from the core enzyme until transcription is initiated. For your second question, the transcription factors will bind the promoter first and then RNA Polymerase will bind to the promoter sequence. The RNA Polymerase will come to the transcription factors 

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