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Frna
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<p>A <b>non-coding RNA</b><span style="color: #000000"> (<b>ncRNA</b>) is a functional RNA molecule that is not translated into a protein. Less-frequently used synonyms are non-protein-coding RNA (npcRNA), non-messenger RNA (nmRNA), small non-messenger RNA (snmRNA) and functional RNA (fRNA). The term <b>small RNA</b> (<b>sRNA</b>) is often used for small bacterial ncRNAs. The DNA sequence from which a non-coding RNA is transcribed as the end product is often called an <b>RNA gene</b> or non-coding RNA gene.</span></p>
<p><span style="color: #000000">Non-coding RNA genes include highly abundant and functionally important RNAs such as transfer RNA (tRNA) and ribosomal RNA (rRNA), as well as RNAs such as snoRNAs, microRNAs, siRNAs and piRNAs and the long ncRNAs that include examples such as Xist and HOTAIR (see here for a more complete list of ncRNAs). The number of ncRNAs encoded within the human genome is unknown, however recent transcriptomic and bioinformatic studies suggest the existence of thousands of ncRNAs.<sup id="cite_ref-pmid15790807_0-0" class="reference"><font size="2">[1]</font></sup><sup id="cite_ref-pmid17571346_1-0" class="reference"><font size="2">[2]</font></sup><sup id="cite_ref-pmid17568003_2-0" class="reference"><font size="2">[3]</font></sup><sup><font size="2">, but see</font></sup> <sup id="cite_ref-3" class="reference"><font size="2">[4]</font></sup> Since many of the newly identified ncRNAs have not been validated for their function, it is possible that many are non-functional.<sup id="cite_ref-pmid15851066_4-0" class="reference"><font size="2">[5]</font></sup></span></p>
<p><table id="toc" class="toc tochidden"> <tbody> <tr> <td> <div id="toctitle"> <h2><span style="color: #000000">Contents</span></h2> <span style="color: #000000"><span class="toctoggle"><font size="2">[</font><font size="2">show</font><font size="2">]</font></span></span></div> <ul style="display: none"> <li class="toclevel-1 tocsection-1"><span style="color: #000000"><span class="tocnumber">1</span> <span class="toctext">History and discovery</span></span></li> <li class="toclevel-1 tocsection-2"><span style="color: #000000"><span class="tocnumber">2</span> <span class="toctext">Biological roles of ncRNA</span> </span> <ul> <li class="toclevel-2 tocsection-3"><span style="color: #000000"><span class="tocnumber">2.1</span> <span class="toctext">ncRNAs in translation</span></span></li> <li class="toclevel-2 tocsection-4"><span style="color: #000000"><span class="tocnumber">2.2</span> <span class="toctext">ncRNAs in RNA splicing</span></span></li> <li class="toclevel-2 tocsection-5"><span style="color: #000000"><span class="tocnumber">2.3</span> <span class="toctext">ncRNAs in gene regulation</span> </span> <ul> <li class="toclevel-3 tocsection-6"><span style="color: #000000"><span class="tocnumber">2.3.1</span> <span class="toctext">trans-acting ncRNAs</span></span></li> <li class="toclevel-3 tocsection-7"><span style="color: #000000"><span class="tocnumber">2.3.2</span> <span class="toctext">cis-acting ncRNAs</span></span></li> </ul> </li> <li class="toclevel-2 tocsection-8"><span style="color: #000000"><span class="tocnumber">2.4</span> <span class="toctext">ncRNAs and genome defense</span></span></li> <li class="toclevel-2 tocsection-9"><span style="color: #000000"><span class="tocnumber">2.5</span> <span class="toctext">ncRNAs and chromosome structure</span></span></li> <li class="toclevel-2 tocsection-10"><span style="color: #000000"><span class="tocnumber">2.6</span> <span class="toctext">Bifunctional RNA</span></span></li> </ul> </li> <li class="toclevel-1 tocsection-11"><span style="color: #000000"><span class="tocnumber">3</span> <span class="toctext">ncRNAs and disease</span> </span> <ul> <li class="toclevel-2 tocsection-12"><span style="color: #000000"><span class="tocnumber">3.1</span> <span class="toctext">Cancer</span></span></li> <li class="toclevel-2 tocsection-13"><span style="color: #000000"><span class="tocnumber">3.2</span> <span class="toctext">Prader&ndashnbsp;Willi syndrome</span></span></li> <li class="toclevel-2 tocsection-14"><span style="color: #000000"><span class="tocnumber">3.3</span> <span class="toctext">Autism</span></span></li> <li class="toclevel-2 tocsection-15"><span style="color: #000000"><span class="tocnumber">3.4</span> <span class="toctext">Cartilage-hair hypoplasia</span></span></li> <li class="toclevel-2 tocsection-16"><span style="color: #000000"><span class="tocnumber">3.5</span> <span class="toctext">Alzheimer's disease</span></span></li> <li class="toclevel-2 tocsection-17"><span style="color: #000000"><span class="tocnumber">3.6</span> <span class="toctext">miR-96 and hearing loss</span></span></li> </ul> </li> <li class="toclevel-1 tocsection-18"><span style="color: #000000"><span class="tocnumber">4</span> <span class="toctext">Distinction between functional RNA (fRNA) and ncRNA</span></span></li> <li class="toclevel-1 tocsection-19"><span style="color: #000000"><span class="tocnumber">5</span> <span class="toctext">See also</span></span></li> <li class="toclevel-1 tocsection-20"><span style="color: #000000"><span class="tocnumber">6</span> <span class="toctext">References</span></span></li> <li class="toclevel-1 tocsection-21"><span style="color: #000000"><span class="tocnumber">7</span> <span class="toctext">External links</span></span></li> </ul> </td> </tr> </tbody></table></p>
<h2><span style="color: #000000"><span id="History_and_discovery" class="mw-headline">History and discovery</span></span></h2>
<div class="rellink boilerplate further"><span style="color: #000000">Further information: History of molecular biology</span></div>
<p><span style="color: #000000">Nucleic acids were first discovered in 1868 by Friedrich Miescher<sup id="cite_ref-5" class="reference"><font size="2">[6]</font></sup> and by 1939 RNA had been implicated in protein synthesis.<sup id="cite_ref-6" class="reference"><font size="2">[7]</font></sup> Two decades later, Francis Crick predicted a functional RNA component which mediated translation; he reasoned that RNA is better suited to base-pair with the mRNA transcript than a pure polypeptide.<sup id="cite_ref-7" class="reference"><font size="2">[8]</font></sup></span></p>
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<div style="width: 252px" class="thumbinner"><span style="color: #000000"><font size="2"><img class="thumbimage" alt="" width="250" height="247" src="http://upload.wikimedia.org/wikipedia/commons/thumb/b/ba/TRNA-Phe_yeast_1ehz.png/250px-TRNA-Phe_yeast_1ehz.png" width="250" height="247" /></font> </span>
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<div class="magnify"><span style="color: #000000"><img alt="" width="15" height="11" src="http://bits.wikimedia.org/skins-1.17/common/images/magnify-clip.png" width="15" height="11" /></span></div>
<span style="color: #000000">The cloverleaf structure of Yeast tRNA<sup><font size="1">Phe</font></sup> (<i>inset</i>) and the 3D structure determined by X-ray analysis.</span></div>
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<h3><span style="color: #000000"><span id="ncRNAs_in_translation" class="mw-headline">ncRNAs in translation</span></span></h3>
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<div style="width: 402px" class="thumbinner"><span style="color: #000000"><img class="thumbimage" alt="" width="400" height="203" src="http://upload.wikimedia.org/wikipedia/commons/thumb/e/e6/NcRNAs-central-dogma.svg/400px-NcRNAs-central-dogma.svg.png" width="400" height="203" /> </span>
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<span style="color: #000000">An illustration of the central dogma of molecular biology annotated with the processes ncRNAs are involved in. RNPs are shown in red, ncRNAs are shown in blue.</span></div>
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<span style="color: #000000">Atomic structure of the 50S Subunit from <i>Haloarcula marismortui</i>. Proteins are shown in blue and the two RNA strands in orange and yellow.<sup id="cite_ref-Ban_21-0" class="reference"><font size="1">[22]</font></sup> The small patch of green in the center of the subunit is the active site.</span></div>
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<h3><span style="color: #000000"><span id="ncRNAs_in_RNA_splicing" class="mw-headline">ncRNAs in RNA splicing</span></span></h3>
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<div style="width: 222px" class="thumbinner"><span style="color: #000000"><img class="thumbimage" alt="" width="220" height="160" src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/18/Yeast_tri-snRNP.jpg/220px-Yeast_tri-snRNP.jpg" width="220" height="160" /> </span>
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<span style="color: #000000">Electron microscopy images of the yeast spliceosome. Note the bulk of the complex is in fact ncRNA.</span></div>
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<h2><span id="External_links" class="mw-headline">External links</span></h2>
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<li><a class="external text" rel="nofollow" href="http://jsm-research.imb.uq.edu.au/rnadb" rel="nofollow"><font color="#3366bb">Comprehensive database of mammalian ncRNAs</font></a></li> <li><a class="external text" rel="nofollow" href="http://rfam.sanger.ac.uk" rel="nofollow"><font color="#3366bb">The Rfam Database</font></a> — a curated list of hundreds of families of related ncRNAs.</li> <li><a class="external text" rel="nofollow" href="http://www.noncode.org/" rel="nofollow"><font color="#3366bb">NONCODE.org</font></a> — a free database of all kinds of noncoding RNAs (except tRNAs and rRNAs).</li> <li><a class="external text" rel="nofollow" href="http://www.ncrnadb.trna.ibch.poznan.pl/" rel="nofollow"><font color="#3366bb">Joint ncRNA Database</font></a> — over 30,000 individual sequences from 99 species of bacteria, archaea and eukaryota</li>
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