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<p><strong>Heterochromatin</strong> is a tightly packed form of DNA. Its major characteristic is that <a href="/wiki/Transcription_(genetics)" title="Transcription (genetics)">transcription</a> is limited. As such, it is a means to control <a href="/wiki/Gene_expression" title="Gene expression">gene expression</a>, through regulation of the transcription initiation.</p><table summary="Contents" id="toc" class="toc"> <tbody> <tr> <td /> </tr> </tbody></table> <p><a name="Structure" id="Structure"></a> </p>
<h2><span class="editsection"></span><span class="mw-headline">Structure</span></h2>
<p><a href="/wiki/Chromatin" title="Chromatin">Chromatin</a> is found in two varieties: <a href="/wiki/Euchromatin" title="Euchromatin">euchromatin</a> and heterochromatin.<sup id="cite_ref-0" class="reference"><a hrefid="#cite_notecite_ref-0" title=""><span>[</span>1<span>]</span></a></sup> Originally, the two forms were distinguished cytologically by how intensely they stained - the former is less intense, while the latter stains intensely, indicating tighter packing. Heterochromatin is usually localized to the periphery of the <a href="/wiki/Cell_nucleus" title="Cell nucleus">nucleus</a>.</p><p>Heterochromatin mainly consists of genetically inactive <a href="/wiki/Satellite_DNA" title="Satellite DNA">satellite sequences</a>,<sup id="cite_ref-1" class="reference"><a hrefid="#cite_notecite_ref-1" title=""><span>[</span>2<span>]</span></a></sup> and many genes are repressed to various extents, although some cannot be expressed in euchromatin at all.<sup id="cite_ref-2" class="reference"><a hrefid="#cite_notecite_ref-2" title=""><span>[</span>3<span>]</span></a></sup> Heterochromatin also replicates later in S phase of the cell cycle than euchromatin, and is found only in eukaryotes. Both <a href="/wiki/Centromere" title="Centromere">centromeres</a> and <a href="/wiki/Telomere" title="Telomere">telomeres</a> are heterochromatic, as is the <a href="/wiki/Barr_body" title="Barr body">Barr body</a> of the second inactivated <a href="/wiki/X_chromosome" title="X chromosome">X chromosome</a> in a female.</p><p><a nameid="Function" idname="Function"></a></p>
<h2><span class="editsection"></span><span class="mw-headline">Function</span></h2>
<p>Heterochromatin is believed to serve several functions, from gene regulation to the protection of the integrity of chromosomes; all of these roles can be attributed to the dense packing of DNA, which makes it less accessible to protein factors that bind DNA or its associated factors. For example, naked double-stranded DNA ends would usually be interpreted by the cell as damaged DNA, triggering <a href="/wiki/Cell_cycle" title="Cell cycle">cell cycle</a> arrest and <a href="/wiki/DNA_repair" title="DNA repair">DNA repair</a>.<sup class="noprint Template-Fact"><span style="white-space: nowrap;" title="This claim needs references to reliable sources since June 2007" style="WHITE-SPACE: nowrap">[<em><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a></em>]</span></sup> Some region of chromatin are very densly packed with fibres displaying a condition comparable to that of the chromosome at mitosis. Heterochromatin is generally clonally inherited; when a cell divides the two daughter cells will typically contain heterochromatin within the same regions of DNA, resulting in <a href="/wiki/Epigenetic_inheritance" title="Epigenetic inheritance" class="mw-redirect">epigenetic inheritance</a>. Variations cause heterochromatin to encroach on adjacent genes or recede from genes at the extremes of domains. Transcribable material may be repressed by being positioned (in <em>cis</em>) at these boundary domains. This gives rise to different levels of expression from cell to cell,<sup id="cite_ref-3" class="reference"><a hrefid="#cite_notecite_ref-3" title=""><span>[</span>4<span>]</span></a></sup> which may be demonstrated by <a href="/wiki/Position-effect_variegation" title="Position-effect variegation">position-effect variegation</a>.<sup id="cite_ref-4" class="reference"><a hrefid="#cite_notecite_ref-4" title=""><span>[</span>5<span>]</span></a></sup> <a href="/wiki/Insulator" title="Insulator">Insulator</a> sequences may act as a barrier in rare cases where constitutive heterochromatin and highly active genes are juxtaposed (e.g. the 5'HS4 insulator upstream of the chicken β-globin locus,<sup id="cite_ref-5" class="reference"><a hrefid="#cite_notecite_ref-5" title=""><span>[</span>6<span>]</span></a></sup> and loci in two <em><a href="/wiki/Saccharomyces" title="Saccharomyces">Saccharomyces</a></em> spp.<sup id="cite_ref-6" class="reference"><a hrefid="#cite_notecite_ref-6" title=""><span>[</span>7<span>]</span></a></sup><sup id="cite_ref-7" class="reference"><a hrefid="#cite_notecite_ref-7" title=""><span>[</span>8<span>]</span></a></sup>).</p><p><a nameid="Constitutive_heterochromatin" idname="Constitutive_heterochromatin"></a></p>
<h2><span class="editsection"></span><span class="mw-headline">Constitutive heterochromatin</span></h2>
<p>All cells of a given species will package the same regions of DNA in <a href="/wiki/Constitutive_heterochromatin" title="Constitutive heterochromatin">constitutive heterochromatin</a>, and thus in all cells any genes contained within the constitutive heterochromatin will be poorly <a href="/wiki/Gene_expression" title="Gene expression">expressed</a>. For example, all human chromosomes <a href="/wiki/Chromosome_1_(human)" title="Chromosome 1 (human)">1</a>, <a href="/wiki/Chromosome_9_(human)" title="Chromosome 9 (human)">9</a>, <a href="/wiki/Chromosome_16_(human)" title="Chromosome 16 (human)">16</a>, and the <a href="/wiki/Y_chromosome" title="Y chromosome">Y chromosome</a> contain large regions of constitutive heterochromatin. In most organisms, constitutive heterochromatin occurs around the chromosome centromere and near telomeres.</p><p><a nameid="Facultative_heterochromatin" idname="Facultative_heterochromatin"></a></p>
<h2><span class="editsection"></span><span class="mw-headline">Facultative heterochromatin</span></h2>
<p><a href="/wiki/Facultative_heterochromatin" title="Facultative heterochromatin" class="mw-redirect">Facultative heterochromatin</a> The regions of DNA packaged in facultative heterochromatin will not be consistent within the cell types of a species, and thus a sequence in one cell that is packaged in facultative heterochromatin (and the genes within poorly expressed) may be packaged in euchromatin in another cell (and the genes within no longer silenced). However, the formation of facultative heterochromatin is regulated, and is often associated with <a href="/wiki/Morphogenesis" title="Morphogenesis">morphogenesis</a> or <a href="/wiki/Cellular_differentiation" title="Cellular differentiation">differentiation</a>. An example of facultative heterochromatin is <a href="/wiki/X-inactivation" title="X-inactivation">X-chromosome inactivation</a> in female mammals: one <a href="/wiki/X_chromosome" title="X chromosome">X chromosome</a> is packaged in facultative heterochromatin and silenced, while the other X chromosome is packaged in euchromatin and expressed.</p><p>Among the molecular components that appear to regulate the spreading of heterochromatin include the <a href="/wiki/Polycomb-group_proteins" title="Polycomb-group proteins">Polycomb-group proteins</a> and non-coding genes such as <a href="/wiki/Xist" title="Xist">Xist</a>. The mechanism for such spreading is still a matter of controversy.<sup id="cite_ref-8" class="reference"><a hrefid="#cite_notecite_ref-8" title=""><span>[</span>9<span>]</span></a></sup></p><p><a nameid="Yeast_heterochromatin" idname="Yeast_heterochromatin"></a></p>
<h2><span class="editsection"></span><span class="mw-headline">Yeast heterochromatin</span></h2>
<p><em><a href="/wiki/Saccharomyces_cerevisiae" title="Saccharomyces cerevisiae">Saccharomyces cerevisiae</a></em>, or budding yeast, is a model <a href="/wiki/Eukaryote" title="Eukaryote">eukaryote</a> and its heterochromatin has been defined thoroughly. Although most of its genome can be characterized as euchromatin, <em>S. cerevisiae</em> has regions of DNA that are transcribed very poorly. These loci are the so-called silent mating type loci (HML and HMR), the rDNA (encoding ribosomal RNA), and the sub-telomeric regions. Fission yeast (<em><a href="/wiki/Schizosaccharomyces_pombe" title="Schizosaccharomyces pombe">Schizosaccharomyces pombe</a></em>) uses another mechanism for heterochromatin formation at its centromeres. Gene silencing at this location depends on components of the <a href="/wiki/RNAi" title="RNAi" class="mw-redirect">RNAi</a> pathway. Double-stranded RNA is believed to result in silencing of the region through a series of steps.</p><p>In the fission yeast <em><a href="/wiki/Schizosaccharomyces_pombe" title="Schizosaccharomyces pombe">Schizosaccharomyces pombe</a></em> two RNAi complexes, the RNAi-induced transcriptional gene silencing (RITS) complex and the RNA-directed RNA polymerase complex (RDRC), are part of a RNAi machinery involved in the initiation, propagation and maintenance of heterochromatin assembly. These two complexes localize in a <a href="/wiki/SiRNA" title="SiRNA" class="mw-redirect">siRNA</a>-dependent manner on chromosomes, at the site of heterochromatin assembly. <a href="/wiki/RNA_polymerase_II" title="RNA polymerase II">RNA polymerase II</a> synthesizes a transcript that serves as a platform to recruit RITS, RDRC and possibly other complexes required for heterochromatin assembly. Both RNAi and an exosome-dependent RNA degradation process contribute to heterochromatic gene silencing. These mechanisms of <em><a href="/wiki/Schizosaccharomyces_pombe" title="Schizosaccharomyces pombe">Schizosaccharomyces pombe</a></em> may occur in other eukaryotes.<sup id="cite_ref-Vavasseur_9-0" class="reference"><a hrefid="#cite_notecite_ref-VavasseurVavasseur_9-9" title="0"><span>[</span>10<span>]</span></a></sup></p><p><a nameid="External_links" idname="External_links"></a></p>
<h2><span class="editsection"></span><span class="mw-headline">External links</span></h2>
<ul>
<li><a title="Boston University" href="/wiki/Boston_University" title="Boston University">Histology at BU</a> <em><a relclass="nofollowexternal text" hreftitle="http://www.bu.edu/histology/p/20102loa.htm" titlerel="nofollow" href="http://www.bu.edu/histology/p/20102loa.htm" class="external text">20102loa</a></em> </li>
</ul>
<p><a nameid="References" idname="References"></a></p>
<h2><span class="editsection"></span><span class="mw-headline">References</span></h2>
<div class="references-small">
<ol class="references">
<li id="cite_note-0"><strong><a href="#cite_ref-0" title="">^</a></strong> <cite styleclass="font-style: normal;Journal" id="CITEREFElgin.2C_S.C.1996" classstyle="JournalFONT-STYLE: normal">Elgin, S.C. (1996). "Heterochromatin and gene regulation in <em>Drosophila</em>". <em><a href="/wiki/Curr._OpinOpin._GenetGenet._DevDev." title="Curr. Opin. Genet. Dev." class="mw-redirect">Curr. Opin. Genet. Dev.</a></em</em> <strong>6</strong>: 193–202. doi:<a hrefspan class="/wiki/Digital_object_identifier" title="Digital object identifierneverexpand">doi10.1016/S0959-437X(96)80050-5</span>. ISSN 0959-437X.</acite>:<span class="neverexpandZ3988"><a reltitle="nofollow" hrefctx_ver="http://dxZ39.doi.org/10.1016%2FS095988-437X2004&rft_val_fmt=info%28963Aofi%2980050-5" title="http://dx.doi.org/10.10162Ffmt%2FS0959-437X3Akev%28963Amtx%2980050-5" class3Ajournal&rft.genre="external text">10article&rft.1016/S0959-437X(96)80050-5</a></span>atitle=Heterochromatin+and+gene+regulation+in+%27%27Drosophila%27%27&rft. <a hrefjtitle="/wiki/International_Standard_Serial_Number" title="International Standard Serial Number">ISSN</a> <a rel%5B%5BCurr.+Opin.+Genet.+Dev.%5D%5D&rft.aulast="nofollow" href="http://worldcatElgin%2C+S.org/issn/0959-437X" titleC.&rft.au="http://worldcatElgin%2C+S.C.&rft.org/issn/0959-437X" classdate="external text">0959-437X</a>.</cite><span title="ctx_ver=Z39.88-20041996&rft_val_fmtrft.volume=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal6&rft.genrepages=article193%E2%80%93202&rftrft_id=info:doi/10.atitle=Heterochromatin+and+gene+regulation+in+1016%272FS0959-437X%27Drosophila2896%27%272980050-5&rft.jtitleissn=%5B%5BCurr.+Opin.+Genet.+Dev.%5D%5D0959-437X&rft.aulastrfr_id=Elgin%2C+Sinfo:sid/en.Cwikipedia.&rft.auorg:Heterochromatin"><span style=Elgin%2C+S.C."DISPLAY: none">&nbsp;rft.date</span></span> </li> <li id=1996&rft"cite_note-1"><strong>^</strong> <cite class="Journal" id="CITEREFLohe.volume=6&rft2C_A.pages=193%E2%80%93202&rft_idR..2C_.27.27et_al..27.271993" style=info"FONT-STYLE:doi/10normal">Lohe, A.R.1016%2FS0959-437X%2896%2980050-5&rft, <em>et al.</em> (1993).issn=0959-437X&quot;rfr_id=info:sid/en.wikipedia.org:Heterochromatin" class="Z3988"Mapping simple repeated DNA sequences in heterochromatin of <em>Drosophila melanogaster<span style="display: none;"/em> quot;. <em>Genetics</spanem></spanstrong> 134</listrong> <li id="cite_note(4): 1149–1174. ISSN 0016-1">6731. PMID 8375654<strong><a href="#cite_ref-1" titlespan class="printonly">^<. http://www.genetics.org/cgi/content/full/134/a4/1149</span>.</strongcite> <cite stylespan class="font-style: normal;Z3988" idtitle="CITEREFLohectx_ver=Z39.2C_A.R..2C_.27.27et_al88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=Mapping+simple+repeated+DNA+sequences+in+heterochromatin+of+%27%27Drosophila+melanogaster%27%27&rft.271993" classjtitle="Journal">Lohe, %5B%5BGenetics+%28journal%29%7CGenetics%5D%5D&rft.aulast=Lohe%2C+A.R., <em>et %2C+%27%27et+al.</em> (1993)%27%27&rft. "<a relau="nofollow" href="http://wwwLohe%2C+A.R.genetics%2C+%27%27et+al.org/cgi/content/full/%27%27&rft.date=1993&rft.volume=134/&rft.issue=4/1149" title&rft.pages="http:/1149%E2%80%931174&rft_id=info:pmid/www8375654&rft.issn=0016-6731&rft_id=http%3A%2F%2Fwww.genetics.org%2Fcgi%2Fcontent%2Ffull%2F134%2F4%2F1149&rfr_id=info:sid/cgi/content/full/134/4/1149en.wikipedia.org:Heterochromatin" class><span style="external textDISPLAY: none">Mapping simple repeated DNA sequences in heterochromatin of <em/span>Drosophila melanogaster</emspan></ali>". <em><a hrefli id="/wiki/Genetics_(journal)cite_note-2" title="Genetics (journal)">Genetics</a>><strong>^</em> <strong>134</strong> (4): 1149–1174. <a hrefcite class="/wiki/International_Standard_Serial_NumberJournal" titleid="International Standard Serial Number">ISSN</a> <a rel=CITEREFLu.2C_B.Y..2C_.27.27et_al..27.272000"nofollow" hrefstyle="httpFONT-STYLE://worldcatnormal">Lu, B.org/issn/0016-6731" title="http://worldcatY.org/issn/0016-6731" class="external text">0016-6731, </aem>et al. <a href="http://wwwem> (2000).ncbi"Heterochromatin protein 1 is required for the normal expression of two heterochromatin genes in Drosophila".nlm.nih.gov<em>Genetics</pubmedem> <strong>155</8375654" title="httpstrong> (2)://www699–708.ncbiISSN 0016-6731.nlm.nih.gov/pubmed/8375654" class="external">PMID 8375654</a>10835392<span class="printonly">. <a rel="nofollow" href="http://www.genetics.org/cgi/content/full/134155/42/1149" title="http:699<//wwwspan>.genetics.org</cgi/content/full/134/4/1149" cite><span class="external freeZ3988" title=">http://www.genetics.org/cgi/content/full/134/4/1149</a></span>.</cite><span title="ctx_verctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=MappingHeterochromatin+simpleprotein+repeated1+is+required+for+the+normal+DNAexpression+sequencesof+intwo+heterochromatin+ofgenes+%27%27Drosophilain+melanogaster%27%27Drosophila&rft.jtitle=%5B%5BGenetics+%28journal%29%7CGenetics%5D%5D&rft.aulast=LoheLu%2C+AB.RY.%2C+%27%27et+al.%27%27&rft.au=LoheLu%2C+AB.RY.%2C+%27%27et+al.%27%27&rft.date=19932000&rft.volume=134155&rft.issue=42&rft.pages=1149699%E2%80%93117493708&rft_id=info:pmid/837565410835392&rft.issn=0016-6731&rft_id=http%3A%2F%2Fwww.genetics.org%2Fcgi%2Fcontent%2Ffull%2F1342F155%2F42F2%2F11492F699&rfr_id=info:sid/en.wikipedia.org:Heterochromatin" class="Z3988"><span style="displayDISPLAY: none;"> </span></span> </li> <li id="cite_note-23"><strong><a href="#cite_ref-2" title="">^</a></strong> <cite styleclass="font-style: normal;Journal" id="CITEREFLu.2C_B.Y..2C_.27.27et_al..27.272000CITEREFFisherMatthias_Merkenschlager2002" classstyle="JournalFONT-STYLE: normal">LuFisher, BAmanda G.Y; Matthias Merkenschlager (April 2002)."Gene silencing, cell fate and nuclear organisation". <em>et alCurr. Opin. Genet. Dev.</em> <strong>12</strong> (20002). : 193"ndash;197. doi:<a relspan class="nofollowneverexpand" href="http:>10.1016/S0959-437X(02)00286-1</wwwspan>.geneticsISSN 0959-437X.org</cgi/content/full/155/2/699cite><span class="Z3988" title="http://wwwctx_ver=Z39.genetics88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.org/cgi/content/full/155/2/699" classgenre="external text">Heterochromatin protein 1 is required for the normal expression of two heterochromatin genes in Drosophila</a>article"amp;rft. <em><a hrefatitle=Gene+silencing%2C+cell+fate+and+nuclear+organisation&rft.jtitle="/wiki/Genetics_(journal)" title="Genetics (journal)">Genetics</a></em> <strong>155</strong> (2): 699%5B%5BCurr.+Opin.+Genet.+Dev.%5D%5D&ndashamp;708rft. <a hrefaulast="/wiki/International_Standard_Serial_Number" titleFisher&rft.aufirst="International Standard Serial Number">ISSN</a> <a relAmanda+G.&rft.au="nofollow" href="http://worldcat.org/issn/0016-6731" titleFisher%2C+Amanda+G.&rft.au="http://worldcatMatthias+Merkenschlager&rft.org/issn/0016-6731" classdate="external text">0016-6731</a>April+2002&rft. <a hrefvolume="http://www12&rft.ncbiissue=2&rft.nlm.nih.gov/pubmed/10835392" titlepages=193%E2%80%93197&rft_id="httpinfo:doi//www10.ncbi1016%2FS0959-437X%2802%2900286-1&rft.nlm.nih.gov/pubmedissn=0959-437X&rfr_id=info:sid/10835392en.wikipedia.org:Heterochromatin" class><span style="externalDISPLAY: none">PMID 10835392 </aspan></span class="printonly">. <a rel/li> <li id="nofollowcite_note-4" href><strong>^</strong> <cite class="http://wwwJournal" id="CITEREFZhimulev.2C_I.F..genetics2C_.org/cgi/content/full/155/2/69927.27et_al..27.271986" titlestyle="httpFONT-STYLE://wwwnormal">Zhimulev, I.F.genetics, <em>et al.org</cgi/content/full/155/2/699" class="external free"em>http://www(December 1986).genetics.org/cgi/content/full/155/2/699"</aem>Cytogenetic and molecular aspects of position effect variegation in Drosophila melanogaster</spanem>".<em>Chromosoma</citeem><span title="ctx_ver=Z39.88-2004strong>94</strong> (6): 492&ndash;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft504.genredoi:<span class=article&rft"neverexpand">10.atitle1007/BF00292759</span>. ISSN 1432-0886.</cite><span class=Heterochromatin+protein+1+is+required+for+the+normal+expression+of+two+heterochromatin+genes+in+Drosophila"Z3988" title="ctx_ver=Z39.88-2004&rft.jtitlerft_val_fmt=info%5B3Aofi%5BGenetics+2Ffmt%28journal3Akev%293Amtx%7CGenetics%5D%5D3Ajournal&rft.aulastgenre=Lu%2C+Barticle&rft.Y.%2C+atitle=%27%27et27Cytogenetic+and+molecular+aspects+of+position+effect+variegation+in+Drosophila+al.melanogaster%27%27&rft.aujtitle=Lu%2C5B%5BChromosoma%5D%5D&rft.aulast=Zhimulev%2C+BI.YF.%2C+%27%27et+al.%27%27&rft.dateau=2000&rftZhimulev%2C+I.volume=155&rftF.issue=2%2C+%27%27et+al.%27%27&rft.pagesdate=699%E2%80%93708December+1986&rft_idrft.volume=info:pmid/1083539294&rft.issnissue=0016-67316&rft_idrft.pages=http492%3AE2%2F80%2Fwww.genetics.org%2Fcgi%2Fcontent%2Ffull%2F155%2F2%2F69993504&rfr_idrft_id=info:siddoi/en10.wikipedia1007%2FBF00292759&rft.orgissn=1432-0886&rfr_id=info:sid/en.wikipedia.org:Heterochromatin" class="Z3988"><span style="displayDISPLAY: none;"> </span></span> </li> <li id="cite_note-35"><strong><a href="#cite_ref-3" title="">^</a></strong> <cite styleclass="font-style: normal;Journal" id="CITEREFFisherMatthias_Merkenschlager2002CITEREFBurgess-Beusse.2C_B.2C_.27.27et_al..27.272002" classstyle="JournalFONT-STYLE: normal">FisherBurgess-Beusse, B, Amanda G<em>et al.; Matthias Merkenschlager </em> (April December 2002). "Gene The insulation of genes from external enhancers and silencing, cell fate and nuclear organisationchromatin". <em><a href="/wiki/CurrProc._OpinNatl Acad._Genet._Dev." title="Curr. Opin. Genet. Dev." class="mw-redirect">Curr. Opin. Genet. DevSci.</a></em> USA</em> <strong>129</strong> (2Suppl 4): 19316433–19716437. doi:<a hrefspan class="neverexpand">10.1073/wikipnas.162342499</Digital_object_identifier" title="Digital object identifier"span>doi. PMID 12154228.</acite>:<span class="neverexpandZ3988"><a reltitle="nofollow" hrefctx_ver="http://dxZ39.doi.org/10.1016%2FS095988-437X2004&rft_val_fmt=info%28023Aofi%2900286-1" title="http://dx.doi.org/10.10162Ffmt%2FS0959-437X3Akev%28023Amtx%2900286-1" class3Ajournal&rft.genre="external text">10article&rft.1016/S0959-437X(02)00286-1</a></span>atitle=The+insulation+of+genes+from+external+enhancers+and+silencing+chromatin&rft. <a hrefjtitle="/wiki/International_Standard_Serial_Number" title="International Standard Serial Number">ISSN</a> <a rel="nofollow" href="http://worldcat%5B%5BProc.+Natl+Acad.org/issn/0959-437X" title="http://worldcat+Sci.org/issn/0959-437X" class="external text">0959-437X</a>.</cite><span title="ctx_ver=Z39.88-2004+USA%5D%5D&rft_val_fmtrft.aulast=infoBurgess-Beusse%2C+B%3Aofi2C+%2Ffmt27%3Akev27et+al.%3Amtx27%3Ajournal27&rft.genreau=article&rft.atitle=GeneBurgess-Beusse%2C+silencingB%2C+cell%27%27et+fate+and+nuclear+organisational.%27%27&rft.jtitledate=%5B%5BCurr.December+Opin.+Genet.+Dev.%5D%5D2002&rft.aulastvolume=Fisher9&rft.aufirstissue=AmandaSuppl+G.4&rft.aupages=Fisher16433%E2%80%2C+Amanda+G.9316437&rftrft_id=info:doi/10.1073%2Fpnas.au=Matthias+Merkenschlager162342499&rft.daterft_id=April+2002info:pmid/12154228&rftrfr_id=info:sid/en.volume=12&rftwikipedia.issueorg:Heterochromatin"><span style=2"DISPLAY: none">&nbsp;rft.pages=193%E2%80%93197&rft_id</span></span> </li> <li id=info:doi/10.1016%2FS0959"cite_note-437X%2802%2900286-1&rft.issn=0959-437X&rfr_id=info:sid6"><strong>^</en.wikipedia.org:Heterochromatin" strong> <cite class="Z3988Journal" id="CITEREFNoma.2C_K..2C_.27.27et_al..27.272001"><span style="displayFONT-STYLE: none;normal"> Noma, K., </spanem>et al.</spanem> </li(August 2001). "transitions in distinct histone H3 methylation patterns at the heterochromatin domain boundaries". <em> Science<li id="cite_note-4"/em><strong>293<a href="#cite_ref-4" title/strong> (5532): 1150–1155. doi:<span class="neverexpand">^10.1126/science.1064150</aspan>. PMID 11498594.</strongcite> <cite stylespan class="font-style: normal;Z3988" idtitle="CITEREFZhimulevctx_ver=Z39.2C_I.F..2C_.27.27et_al..27.271986" class88-2004&rft_val_fmt="Journal">Zhimulev, Iinfo%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.F., <em>et al.</em> (December 1986). genre=article"amp;<em>Cytogenetic and molecular aspects of position effect variegation rft.atitle=transitions+in Drosophila melanogaster</em>+distinct+histone+H3+methylation+patterns+at+the+heterochromatin+domain+boundaries"amp;rft. <em><a hrefjtitle="/w/index.php?title=Chromosoma%5B%5BScience+%28journal%29%7CScience%5D%5D&actionrft.aulast=edit&redlink=1" titleNoma%2C+K.%2C+%27%27et+al.%27%27&rft.au="Chromosoma (page does not exist)" class="new">Chromosoma</a></em> <strong>94</strong> (6): 492Noma%2C+K.%2C+%27%27et+al.%27%27&ndashamp;504rft. <a hrefdate="/wiki/Digital_object_identifier" titleAugust+2001&rft.volume="Digital object identifier">doi</a>:<span class293&rft.issue="neverexpand"><a rel5532&rft.pages="nofollow" href1150%E2%80%931155&rft_id="httpinfo://dx.doi.org/10.10071126%2FBF00292759" title2Fscience.1064150&rft_id="httpinfo:pmid/11498594&rfr_id=info:sid/dxen.doiwikipedia.org/10.1007%2FBF00292759:Heterochromatin" class><span style="external textDISPLAY: none">10.1007/BF00292759 </aspan></span>. <a href="/wiki/International_Standard_Serial_Number" titleli> <li id="International Standard Serial Number"cite_note-7">ISSN<strong>^</astrong> <a relcite class="nofollowJournal" hrefid="http://worldcatCITEREFDonze.2C_D._.26_R.T.org/issn/1432-0886_Kamakaka2000" titlestyle="httpFONT-STYLE://worldcat.org/issn/1432-0886" class="external text">1432-0886</anormal">Donze, D.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rftR.T. Kamakaka (2000).genre=article&quot;rft.atitle=%27%27Cytogenetic+RNA polymerase III and+molecular+aspects+of+position+effect+variegation+RNA polymerase II promoter complexes are heterochromatin barriers in+Drosophila+melanogaster%27%27<em>Saccharomyces cerevisiae</em>&quot;rft.jtitle=%5B%5BChromosoma%5D%5D<em>Embo J.</em> <strong>20</strong>: 520&ndash;rft31.aulastdoi:<span class=Zhimulev%2C+I"neverexpand">10.F1093/emboj/20.%2C+%27%27et+al3.%27%27&rft520</span>.au</cite><span class=Zhimulev%2C+I.F"Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%2C+3Aofi%272Ffmt%27et+al.3Akev%273Amtx%273Ajournal&rft.dategenre=December+1986article&rft.volumeatitle=94RNA+polymerase+III+and+RNA+polymerase+II+promoter+complexes+are+heterochromatin+barriers+in+%27%27Saccharomyces+cerevisiae%27%27&rft.issuejtitle=6&rft%5B%5BEmbo+J.pages=492%E25D%80%935045D&rft_idrft.aulast=info:doi/10Donze%2C+D.1007+%2FBF0029275926+R.T.+Kamakaka&rft.issnau=1432-0886Donze%2C+D.+%26+R.T.+Kamakaka&rfr_idrft.date=info:sid/en2000&rft.wikipediavolume=20&rft.org:Heterochromatin" classpages="Z3988"><span style520%E2%80%9331&rft_id="displayinfo: none;">doi/10.1093%2Femboj%2F20.3.520 amp;rfr_id=info:sid/en.wikipedia.org:Heterochromatin"><span style="DISPLAY: none"> </span></span> </li> <li id="cite_note-58"><strong><a href="#cite_ref-5" title="">^</astrong>Talbert PB, Henikoff S. Spreading of silent chromatin: inaction at a distance. Nat Rev Genet. 2006 Oct;7(10):793-803. </strongli> <cite styleli id="fontcite_note-style: normal;Vavasseur-9"><strong>^</strong> <cite class="book" id="CITEREFBurgess-BeusseCITEREFVavasseur_et_al.2C_B.2C_.27.27et_al..27.2720022008" classstyle="Journal">Burgess-Beusse, B, <emFONT-STYLE: normal">Vavasseur et al.</em> (December 20022008). "The insulation Heterochromatin Assembly and Transcriptional Gene Silencing under the Control of genes Nuclear RNAi: Lessons from external enhancers and silencing chromatinFission Yeast". <em>RNA and the Regulation of Gene Expression: A Hidden Layer of Complexity<a href="/wiki/Procem>._Natl_AcadCaister Academic Press._SciISBN 978-1-904455-25-7._USA" title</cite><span class="Proc. Natl Acad. Sci. USA" class="mw-redirect">Proc. Natl Acad. Sci. USA</a></em> <strong>9</strong> (Suppl 4): 16433–16437. <a href="/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<span class="neverexpand"><a rel="nofollow" href="http://dx.doi.org/10.1073%2Fpnas.162342499" title="http://dx.doi.org/10.1073%2Fpnas.162342499" class="external text">10.1073/pnas.162342499</a></span>. <a href="http://www.ncbi.nlm.nih.gov/pubmed/12154228" title="http://www.ncbi.nlm.nih.gov/pubmed/12154228" class="external">PMID 12154228</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=The+insulation+of+genes+from+external+enhancers+and+silencing+chromatin&rft.jtitle=%5B%5BProc.+Natl+Acad.+Sci.+USA%5D%5D&rft.aulast=Burgess-Beusse%2C+B%2C+%27%27et+al.%27%27&rft.au=Burgess-Beusse%2C+B%2C+%27%27et+al.%27%27&rft.date=December+2002&rft.volume=9&rft.issue=Suppl+4&rft.pages=16433%E2%80%9316437&rft_id=info:doi/10.1073%2Fpnas.162342499&rft_id=info:pmid/12154228&rfr_id=info:sid/en.wikipedia.org:Heterochromatin" class="Z3988"><span style="display: none;"> </span></span> </li> <li id="cite_note-6"><strong><a href="#cite_ref-6" title="">^</a></strong> <cite style="font-style: normal;" id="CITEREFNoma.2C_K..2C_.27.27et_al..27.272001" class="Journal">Noma, K., <em>et al.</em> (August 2001). "transitions in distinct histone H3 methylation patterns at the heterochromatin domain boundaries". <em><a href="/wiki/Science_(journal)" title="Science (journal)">Science</a></em> <strong>293</strong> (5532): 1150–1155. <a href="/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<span class="neverexpand"><a rel="nofollow" href="http://dx.doi.org/10.1126%2Fscience.1064150" title="http://dx.doi.org/10.1126%2Fscience.1064150" class="external text">10.1126/science.1064150</a></span>. <a href="http://www.ncbi.nlm.nih.gov/pubmed/11498594" title="http://www.ncbi.nlm.nih.gov/pubmed/11498594" class="external">PMID 11498594</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=transitions+in+distinct+histone+H3+methylation+patterns+at+the+heterochromatin+domain+boundaries&rft.jtitle=%5B%5BScience+%28journal%29%7CScience%5D%5D&rft.aulast=Noma%2C+K.%2C+%27%27et+al.%27%27&rft.au=Noma%2C+K.%2C+%27%27et+al.%27%27&rft.date=August+2001&rft.volume=293&rft.issue=5532&rft.pages=1150%E2%80%931155&rft_id=info:doi/10.1126%2Fscience.1064150&rft_id=info:pmid/11498594&rfr_id=info:sid/en.wikipedia.org:Heterochromatin" class="Z3988"><span style="display: none;"> </span></span> </li> <li id="cite_note-7"><strong><a href="#cite_ref-7" title="">^</a></strong> <cite style="font-style: normal;" id="CITEREFDonze.2C_D._.26_R.T._Kamakaka2000" class="Journal">Donze, D. & R.T. Kamakaka (2000). "RNA polymerase III and RNA polymerase II promoter complexes are heterochromatin barriers in <em>Saccharomyces cerevisiae</em>". <em><a href="/w/index.php?title=Embo_J.&action=edit&redlink=1" title="Embo J. (page does not exist)" class="new">Embo J.</a></em> <strong>20</strong>: 520–31. <a href="/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<span class="neverexpand"><a rel="nofollow" href="http://dx.doi.org/10.1093%2Femboj%2F20.3.520" title="http://dx.doi.org/10.1093%2Femboj%2F20.3.520" class="external text">10.1093/emboj/20.3.520</a></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=RNA+polymerase+III+and+RNA+polymerase+II+promoter+complexes+are+heterochromatin+barriers+in+%27%27Saccharomyces+cerevisiae%27%27&rft.jtitle=%5B%5BEmbo+J.%5D%5D&rft.aulast=Donze%2C+D.+%26+R.T.+Kamakaka&rft.au=Donze%2C+D.+%26+R.T.+Kamakaka&rft.date=2000&rft.volume=20&rft.pages=520%E2%80%9331&rft_id=info:doi/10.1093%2Femboj%2F20.3.520&rfr_id=info:sid/en.wikipedia.org:Heterochromatin" class="Z3988"><span style="display: none;"> </span></span> </li> <li id="cite_note-8"><strong><a href="#cite_ref-8" title="">^</a></strong> Talbert PB, Henikoff S. Spreading of silent chromatin: inaction at a distance. Nat Rev Genet. 2006 Oct;7(10):793-803. </li> <li id="cite_note-Vavasseur-9"><strong><a href="#cite_ref-Vavasseur_9-0" title="">^</a></strong> <cite style="font-style: normal;" id="CITEREFVavasseur_et_al.2008" class="book">Vavasseur et al. (2008). <a rel="nofollow" href="http://www.horizonpress.com/rnareg" title="http://www.horizonpress.com/rnareg" class="external text">"Heterochromatin Assembly and Transcriptional Gene Silencing under the Control of Nuclear RNAi: Lessons from Fission Yeast"</a>. <em>RNA and the Regulation of Gene Expression: A Hidden Layer of Complexity</em>. Caister Academic Press. <a rel="nofollow" href="http://www.horizonpress.com/rnareg" title="http://www.horizonpress.com/rnareg" class="external textZ3988">ISBN 978-1-904455-25-7</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.btitle=Heterochromatin+Assembly+and+Transcriptional+Gene+Silencing+under+the+Control+of+Nuclear+RNAi%3A+Lessons+from+Fission+Yeast&rft.atitle=RNA+and+the+Regulation+of+Gene+Expression%3A+A+Hidden+Layer+of+Complexity&rft.aulast=Vavasseur+et+al.&rft.au=Vavasseur+et+al.&rft.date=2008&rft.pub=Caister+Academic+Press&rfr_id=info:sid/en.wikipedia.org:Heterochromatin" class="Z3988"><span style="displayDISPLAY: none;"> </span></span> </li>
</ol>
</div>
<ul>
<li>Z. Avramova <em>Heterochromatin in Animals and Plants. Similarities and Differences</em>. <a rel="nofollow" href="http://www.plantphysiol.org/cgi/content/full/129/1/40" title="http://www.plantphysiol.org/cgi/content/full/129/1/40" class="external text">Plant Physiology</a> May 2002, Vol. 129, pp. 40-49. </li> <li><cite styleclass="font-style: normal;Journal" id="CITEREFCaron.2C_H..2C_.27.27et_al..27.272001" classstyle="JournalFONT-STYLE: normal">Caron, H., <em>et al.</em> (2001). "The Human Transcriptome Map: Clustering of Highly Expressed Genes in Chromosomal Domains". <em><a href="/wiki/Science_(journal)" title="Science (journal)">Science</a></em> <strong>291</strong> (5507): 1289–1292. <a href="/wiki/Digital_object_identifier" title="Digital object identifier">doi</a>:<span class="neverexpand"><a rel="nofollow" href="http://dx.doi.org/10.1126%2Fscience.1056794" title="http://dx.doi.org/10.1126%2Fscience.1056794" class="external text">10.1126/science.1056794</a></span>. <a href="http://www.ncbi.nlm.nih.gov/pubmed/11181992" title="http://www.ncbi.nlm.nih.gov/pubmed/11181992" class="external">PMID 11181992</a>.</cite><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.atitle=The+Human+Transcriptome+Map%3A+Clustering+of+Highly+Expressed+Genes+in+Chromosomal+Domains&rft.jtitle=%5B%5BScience+%28journal%29%7CScience%5D%5D&rft.aulast=Caron%2C+H.%2C+%27%27et+al.%27%27&rft.au=Caron%2C+H.%2C+%27%27et+al.%27%27&rft.date=2001&rft.volume=291&rft.issue=5507&rft.pages=1289%E2%80%931292&rft_id=info:doi/10.1126%2Fscience.1056794&rft_id=info:pmid/11181992&rfr_id=info:sid/en.wikipedia.org:Heterochromatin" class="Z3988"><span style="displayDISPLAY: none;"> </span></span> </li>
</ul>
<p><br />
<p>동의어</p>
<ul>
<li>한글 : [[이질염색질]]</li>
</ul>
<p>정의</p>
<ul>
<li>염색체 물질의 일부로 유전자 발현에는 관여하지 않지만 대사 활동, 전사, 세포분열 등에 작용함.</li>
</ul>