Regular histone H2B is only added to nucleosomes during the S-phase of the cell cycle when DNA is replicated; histone H2B isoforms can be added to nucleosomes at other times during the cell cycle.
A histona H2B común só se engade aos nucleosomas durante a fase S do ciclo celular, cando o ADN está replicándose; as isoformas da histona H2B poden engadirse ao nucleosoma noutros momentos do ciclo celular.