Extended Data Fig. 1 | Assembly and cryo-EM of PARP2–HPF1 bound to
mononucleosomes. a, b, SDS–PAGE (a) and native gel (b) showing the PARP2–
HPF1–nucleosome complex assembly for cryo-EM. Note the shift in the PARP2–
nucleosome complex migration upon binding of HPF1 in b. c, SDS–PAGE and
immunoblotting showing PARP2 PARylation of nucleosomes. HPF1 is required
for H3 PARylation. d, Representative cryo-EM micrograph collected with Titan
Krios electron microscope at 300 keV. Bridging of two nucleosomes by PARP2–
HPF1 is clearly visible in the raw data. Complex particles in multiple
orientations are visible. e, Representative 2D class averages showing two
nucleosomes bridged by PARP2–HPF1. Two nucleosomes are positioned in an
almost perpendicular orientation. PARP2–HPF1 density between two
nucleosomes is clearly visible. Many details in nucleosomes are visible in 2D
class averages. For gel source data, see Supplementary Fig. 1.