Figure 3.
DNA looping during histone transfer. (a) AFM images of complexes where the histones contact both the upstream and downstream DNA. (b) Free DNA length in the presence of NTPs (all concentrations) in complexes where Pol II is in the process of transcribing the nucleosome (the length of DNA between Pol II and the nucleosome is less than 5 nm apart) and (c) complexes where Pol II has started transcription, but has not yet reached the nucleosome. Insets show the presumed structures of each population, with Pol II in blue, the DNA in black, and the histones in brown; the pink shading reflects the apparent broadening of the molecules due to the geometry and size of the AFM tip. Numbers indicate the mean and standard deviations of the total free DNA lengths.