Histone H3 and H4 are the core components of the nucleosome. H3 and H4 assemble H3/H4 tetramer, and H3/K4 tetramer combines with two H2A/H2B dimers to form histone octamer. The histone octamer is wrapped around by 146 bp DNA to assemble a nucleosome, which is the basic structural unit of chromatin in vivo.
