Electrophoretic mobility shift assay visualizing the signal from the labeled DNA incorporated into the nucleosomes (Cy5, 633 nm). All reactions included 150 fmoles of nucleosomes, 3 μM Nhp6, and 2 μM of the indicated Spt6 or Spn1 proteins. Migration positions of bound and unbound nucleosomes are indicated. Addition of Spn1 reduced the amount of Spt6-nucleosome complex from 37% of the total signal in lane 2 to 3.2% in lane 5 (9% remaining), but Spn1-R263D only reduced it to 28% (76% remaining). Spt6-F249K formed a lower amount of stable complex (18%) but Spn1 was less effective at inhibiting this (6% bound, or 36% of the original signal remaining comparing lanes 8 and 9) than it was with WT Spt6 (9% of the original signal remaining).