FL PFV and PFV IN(ΔCTD) intasome integration to trypsinized nucleosomes.A, 601 nucleosomes were treated with trypsin to remove the histone tails (–Tails). FL or PFV IN(ΔCTD) intasomes were added to +Tails or –Tails nucleosomes in the presence of 110 mM NaCl. Integration products were analyzed by denaturing PAGE. The DNA size marker on the left is expressed as the nucleosome positions relative to the dyad. B, the total integration of each intasome to the 601 nucleosomes was calculated as the percentage of fluorescent signal in each lane below the unreacted target. C, integration efficiencies at each cluster –59, –37, +36, and +47 were calculated as the percentage of the fluorescent signal in each lane. Black circles indicate values from each experiment. Error bars indicate the standard deviation between at least three experiments with at least two independent PFV intasome and nucleosome preparations.