Nucleosome

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I. Introduction

dsDNA is a negatively charged polyanion. It must be packed into a form which somehow minimizes the significant electrostatic repulsive forces. It does so in Eukaryotes by packing around a core of positively charged histone proteins (2 copies each of H2A, 2B, 3 and 4) into a structure called the nucleosome.

For more information see Biochemistry Online: Chapter 5D - Binding and the Control of Gene Transcription

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II. General Structure

Wireframe
View DNA
DNA with major and minor groves; protein wireframe
Octomeric Protein Core (Cartoon): 2 subunits each of H2A (red), H2B (orange), H3 (green), and H4 (purple)
Protein (cartoon) interacting with DNA
Protein (spacefill) interacting with DNA
Protein (backbone), Lys and Arg (spacefill) interacting with DNA