Histones

Histones are specific proteins that are found in eukariotic cells nuclei. In fact, their molecular weight is approximatedly the same as DNA's mass. DNA binds to these alkaline proteins, which play an extremely important role in gene regulation. In order to transcription occur properly, DNA requires specific proteins that release it form histones, otherwise transcription becomes impossible. As histones are so highly alkaline, negatively charged DNA easily binds with them, agreggating with 5 types of histones: H2A, H2B, H3, H4 and H1, creating a superstructure we define as nucleossomes.

Fig 1 - Nucleossome core particle bound to DNA (Science Photo)

Bibliography

 Cooper, G.M. , Hausman, R. E., 2009, The Cell, A Molecular Approach, 5th ed,Sinauer