What other factors bind to the complex in a defined order to extend the length and protect the DNA region?

-TFIIB, TFIIE, and TFIIH are required to melt DNA to allow polymerase movement. -Phosphorylation of the CTD is required for promoter clearance and elongation to begin. -Further phosphorylation of the CTD is required at some promoters to end pausing and abortive initiation. RNA polymerase II binds to the complex, it may initiate transcription.