Fig. 5.

The longer N-terminal tail of Ctr9 is essential for its binding to Paf1. a Structural-based sequence alignment of the N-terminal fragments of Ctr9 in various species. In this alignment, the secondary structures of human CTR9^(1–38) and yeast Ctr9^(1–53) are shown at the top and bottom, respectively, and conserved residues are shaded in red. The amino acids 1–16 of yeast Ctr9, which were deleted in the GFP-Ctr9(N16Δ) construct [used in b], are marked with a dotted blue box. The amino acids Y10, P11, M13, E14, and W15 of Ctr9 involved in its binding to Paf1 are marked by orange stars. b Co-IP experiments testing the interactions between Ctr9 WT or Ctr9(N16Δ) mutant and Paf1. Extracts were prepared from HEK293T cells transfected with various combinations of plasmids, as indicated. The bottom panel shows 3% of the Myc fusion proteins for each IP. Uncropped blots are shown in Supplementary Fig. 8