Nucleosome

Exploring the Structure

An intact nucleosome may be viewed in the PDB entry 1aoi. The picture here shows the eight histone proteins as tubes that follow the protein chain, and shows the DNA as thinner tubes that follow the two strands as they circle around the protein octamer. The tails of the eight protein chains, seen extending outward from the center, are actually longer in reality. But, since they are so long and flexible, they are disordered in the crystal and cannot be seen. The one long chain at lower left gives a good indication of what the others might look like, if we were able to see the nucleosome inside a cell. Keep in mind that this structure only includes a short piece of DNA. In reality, these little nucleosomes are arrayed by the millions along long strands of DNA.

This illustration was created by RasMol. You can create similar pictures by clicking on the PDB accession code above and then clicking "View Structure."