User:Madeleine Wilson/Sandbox 1: Difference between revisions
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===Histone Methylation=== | ===Histone Methylation=== | ||
[[Image:human_nucleosome_ray_trace.png|200 px| right| thumb|Human nucleosome]] | [[Image:human_nucleosome_ray_trace.png|200 px| right| thumb|Human nucleosome]] | ||
Histone proteins aid in the packing of DNA for the purpose of compacting the genome in the nucleus of the cell and regulating physical accessibility of genes for transcription. The protein itself is an octamer made of heterodimer core proteins H2a, H2b, H3, and H4, with H1 and H5 acting as linker proteins. About 145-157 base pairs wind around a histone core protein. <ref name="DesJarlais">PMID: 26745824</ref> Modifications to histone core proteins can affect the accessibility of genes in the genome and their ability to be transcribed. Some of these modifications include methylation/demethylation, acetylation/deacetylation, and ubiquitination/deubiquitination. | Histone proteins aid in the packing of DNA for the purpose of compacting the genome in the nucleus of the cell and regulating physical accessibility of genes for transcription. The protein itself is an octamer made of heterodimer core proteins H2a, H2b, H3, and H4, with H1 and H5 acting as linker proteins. About 145-157 base pairs wind around a histone core protein. <ref name="DesJarlais">PMID: 26745824</ref> Modifications to histone core proteins can affect the accessibility of genes in the genome and their ability to be transcribed. Some of these modifications include methylation/demethylation, acetylation/deacetylation, and ubiquitination/deubiquitination. <ref name="Lun">DOI: 10.1016/j.apsb.2013.04.007</ref> | ||
Specifically, histone methylation is associated with gene activation. | Specifically, histone methylation is associated with gene activation. <ref name="Dong">PMID: 23566087</ref> Many domain families fall under the Histone methylase family, one of these enzymes being the <scene name='81/811092/Set7_rotate/4'>SET7 domain</scene> family, which can target H3, H4, or H2a; each of these methylation sites can have different effects on gene expression within the genome. Typically, methylation of some of these sites are always present on both active and inactive genes, extra methylations required for activity. <ref name="Xiao">doi:10.1038/nature01378</ref> Some tumor related genes such as p53 are site specifically methylated to promote biological function (5), whereas hypomethylation of CpG is linked to tumor genesis. <ref name="Lun" /> A particular enzyme in the SET7 domain family is lysine methyltransferase, which acts on the histone by adding a methyl group to Lys4 on H3; the addition results in promotion of gene unwinding and gene transcription. (4,3) | ||
==KMT Structure== | ==KMT Structure== | ||
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<references/> | <references/> | ||
3. Dong, X.; Weng, Z. The correlation between histone modifications and gene expression. Epigenomics 2013, 5: 113-6. | 3. Dong, X.; Weng, Z. The correlation between histone modifications and gene expression. Epigenomics 2013, 5: 113-6. | ||
