Classes and variants thumb|270px|Histone heterooctamer (H3,H4,H2A,H2B) + DNA fragment, Frog Five major families of histone proteins exist: H1/H5, H2A, H2B, H3, and H4. Histones H2A, H2B, H3 and H4 are known as the core or nucleosomal histones, while histones H1/H5 are known as the linker histones.
Classes and variants thum,b|270px|Histone heterooctamer (H3H4,H2A,H2B) + DNA fragment, Frog, Five major families of histone proteins exist: H1/H5 H2A, H2B, H3 and H4. Histones H2A, H2B, H3 and H4 are known as the core or nucleosomal histones, while histones H1/H5 are known as the linker histones.