TFIIH generates a six-base-pair open complex during RNAP II transcription initiation and start-site scanning.

Tomko E.J., Fishburn J., Hahn S., & Galburt E.A. (2017). “TFIIH generates a six-base-pair open complex during RNAP II transcription initiation and start-site scanning.” Nat Struct Mol Biol. 2017 Dec;24(12):1139-1145. doi: 10.1038/nsmb.3500. Epub 2017 Nov 6. (Abstract)