Histone octamer

A histone octamer is an octamer of the histones found at the center of a nucleosome core particle. It consists of 2 copies of each of the four core histone proteins (H2A, H2B, H3 and H4). The octamer assembles when a tetramer, containing two copies of both H3 and H4, complexes with two H2A/H2B dimers. These histones of the histone octamer all contain N-terminal tails that emanate from their central histone folds, and core domains with the C-terminals. The core domains are hydrophobic.