Nucleosome structure
From Proteopedia
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[[es:Nucleosome structure (Spanish)]] | [[es:Nucleosome structure (Spanish)]] | ||
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| - | <Structure load='1aoi' size='350' frame='true' align='right' caption='Nucleosome [[1aoi]]' scene='60/602771/ | + | <Structure load='1aoi' size='350' frame='true' align='right' caption='Nucleosome [[1aoi]]' scene='60/602771/Nucleosoma/3'/> |
<big><big>'''Nucleosomes''' are the basic building blocks of '''chromatin fibers'''. A nucleosome consists of a core containing '''an octamer of histone proteins''' and a '''DNA''' molecule 146 bp long wound around this core in two complete turns. | <big><big>'''Nucleosomes''' are the basic building blocks of '''chromatin fibers'''. A nucleosome consists of a core containing '''an octamer of histone proteins''' and a '''DNA''' molecule 146 bp long wound around this core in two complete turns. | ||
| - | The histone protein octamer includes four types of proteins: <scene name='60/602771/Histonah2a/1'>H2A</scene>, <scene name='60/602771/Histonah2b/1'>H2B</scene>, <scene name='60/602771/Histonah3/1'>H3</scene> and <scene name='60/602771/Histonah4/1'>H4</scene>. Histone proteins are organized in dimers so: | + | The <scene name='60/602771/Proteinas/5'>histone protein octamer</scene> includes four types of proteins: <scene name='60/602771/Histonah2a/1'>H2A</scene>, <scene name='60/602771/Histonah2b/1'>H2B</scene>, <scene name='60/602771/Histonah3/1'>H3</scene> and <scene name='60/602771/Histonah4/1'>H4</scene>. Histone proteins are organized in dimers so: |
*Two H3-H4 dimers | *Two H3-H4 dimers | ||
Revision as of 18:32, 17 February 2016
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Nucleosomes are the basic building blocks of chromatin fibers. A nucleosome consists of a core containing an octamer of histone proteins and a DNA molecule 146 bp long wound around this core in two complete turns. The includes four types of proteins: , , and . Histone 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 main secondary structure in is .
If we highlight the different types of amino acid residues on the we can see that and are arranged so positively charged residues are in , where they can form ionic interactions (salt bridges) with . This distribution of electric charges stabilizes the whole structure.
See Also
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.
