NCIt definition : Proteins in the core histone families, histone H2A and histone H2B represent 2 of
the 4 families of histones found in the core of nucleosomes. Histones in the H2A family
dimerize with those in the H2B family, then two H2A/H2B dimers can associate with
a tetramer containing 2 proteins from the histone H3 family and 2 proteins from the
histone H4 family to form the octameric nucleosome core. The octameric complex is
the basic unit for eukaryotic DNA packaging.;