Our figure shows eukaryotic (yeast) RNA polymerase. Red and blue indicate negative and positive charges, respectively. A large positively charged cleft where DNA binds is visible at the top of the image.
The image below shows a close up of the active site in RNA polymerase II bound to both dATP and dCTP, which bind at different locations. The tri-phosphate and ribose regions bind RNA polymerase in the same location.
