Nucleosome structure
From Proteopedia
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The more widespread secondary structure in <scene name='60/602771/Octamero/2'>histonic proteins</scene> is <scene name='60/602771/Secondarystructure/1'>alfa helix</scene>. | The more widespread secondary structure in <scene name='60/602771/Octamero/2'>histonic proteins</scene> is <scene name='60/602771/Secondarystructure/1'>alfa helix</scene>. | ||
| - | If we situate the different types of amino acid residues in <scene name='60/602771/Esqueleto/1'>protein skeleton</scene> we can see that <scene name='60/602771/Residuosnegativos/1'>negatively charged residues | + | If we situate the different types of amino acid residues in <scene name='60/602771/Esqueleto/1'>protein skeleton</scene> we can see that <scene name='60/602771/Residuosnegativos/1'>negatively charged residues</scene> and <scene name='60/602771/Residuospositivos/1'>positively charged residues</scene> are arranged so positively charged residues are in peripherycal positions <scene name='60/602771/Periferia/1'>peripherycal positions</scene>, where they can stablish ionic interations with <scene name='60/602771/Interacciones/1'>phosphate groups on DNA molecule</scene>. Such electric charges distribution, gives stability to the whole structure. |
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Revision as of 12:35, 9 February 2016
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Nucleosome is the basic structure of chromatin fiber. A nucleosome consists of a core with a histonic proteins octamer and a DNA molecule 146 bp long wound around this core in two complete turns. Histonic protein octamer includes four types of proteins: , , y . Histonic proteins are organized in dimers so:
- Two H3-H4 dimers
- Two H2A-H2B dimers
- molecule wound in around octamer. Some complete the whole structure.
The more widespread secondary structure in is .
If we situate the different types of amino acid residues in we can see that and are arranged so positively charged residues are in peripherycal positions , where they can stablish ionic interations with . Such electric charges distribution, gives stability to the whole structure.
References
This page is based on 1aoi file from Proteopedia.
1aoi is a 10 chain structure with sequence from Xenopus laevis. The July 2000 RCSB PDB Molecule of the Month feature on Nucleosome by David S. Goodsell is 10.2210/rcsb_pdb/mom_2000_7. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
