Write here any specific comment/note about figures in the paper (this could be related to the way data are displayed and your ability to understand the results just by looking at the figures). 
Whilst it is fantastic that the authors decided to share their manuscript as a preprint, it was very difficult to conduct a thorough review of the work without access to the supplementary files and data which are referred to extensively throughout.
The figures are generally well presented, in particular the structural models are clear, even when complicated structural overlays and alignments are shown.
The western blot images look somewhat distorted throughout. For Figure6B, background and band contrast is variable across blots which are being directly compared and the band intensity for the phosphorylation site detection is very low. p2116 panel appears to have artifactual distortion in the background as do Figure 7A&B. Figure 7C in the top right panel has variable background. Shadows surround the bands of EZH2 in the bottom panels of this figure.
The data presented in figure 6B, 7A,B and C are not compelling enough to match the strong statements in the manuscript.
In figure 6B, the immunoblot is normalized against the total concentration of HTT. Validation of the antibodies generated should be provided or referenced to assure readers that the phosphorylation specific antibodies are binding huntingtin with appropriate affinity, specificity and stoichiometry.