Nucleosome: Histone Octamer and Wrapping DNA

Packaging of DNA into chromosomes is achieved through the nucleosome, the basic chromatin unit. In a nucleosome, the core octamer of histones, composed of two H3(red)-H4(green) and H2A(orange)- H2B(blue), is wrapped by the 146 bp DNA in two turns (1AOI.pdb; ref. Luger et al. Nature v389, 251).