TABLE 1:

Particle analysis from electron micrographs.

	Particle number (per image)
Sample	Cryo-EM grid	Negative stain
CENP-A nucleosome	<10	290
Complex AN	700	460
Complex ANC	800	N/A

Particles on a cryo-EM micrograph were picked and counted by using nucleosome-like two-dimensional classes as reference in Relion. Particles on images obtained from negative-stained grids were picked and counted by “dogPicker,” where nucleosomes were defined by a diameter of ∼10 nm. No negative staining EM grids were obtained for complex ANC.