nih-gov/www.ncbi.nlm.nih.gov/books/NBK2334/index.html?report=reader

97 lines
27 KiB
Text

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" class="no-js no-jr">
<head>
<!-- For pinger, set start time and add meta elements. -->
<script type="text/javascript">var ncbi_startTime = new Date();</script>
<!-- Logger begin -->
<meta name="ncbi_db" content="books">
<meta name="ncbi_pdid" content="book-part">
<meta name="ncbi_acc" content="NBK2334">
<meta name="ncbi_domain" content="coffeebrk">
<meta name="ncbi_report" content="reader">
<meta name="ncbi_type" content="fulltext">
<meta name="ncbi_objectid" content="">
<meta name="ncbi_pcid" content="/NBK2334/?report=reader">
<meta name="ncbi_pagename" content="RNA surveillance: watching the defectives - Coffee Break - NCBI Bookshelf">
<meta name="ncbi_bookparttype" content="chapter">
<meta name="ncbi_app" content="bookshelf">
<!-- Logger end -->
<!--component id="Page" label="meta"/-->
<script type="text/javascript" src="/corehtml/pmc/jatsreader/ptpmc_3.22/js/jr.boots.min.js"> </script><title>RNA surveillance: watching the defectives - Coffee Break - NCBI Bookshelf</title>
<meta charset="utf-8">
<meta name="apple-mobile-web-app-capable" content="no">
<meta name="viewport" content="initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no">
<meta name="jr-col-layout" content="auto">
<meta name="jr-prev-unit" content="/books/n/coffeebrk/A18/?report=reader">
<meta name="jr-next-unit" content="/books/n/coffeebrk/A16/?report=reader">
<meta name="bk-toc-url" content="/books/n/coffeebrk/?report=toc">
<meta name="robots" content="INDEX,FOLLOW,NOARCHIVE">
<meta name="citation_inbook_title" content="Coffee Break: Tutorials for NCBI Tools [Internet]">
<meta name="citation_title" content="RNA surveillance: watching the defectives">
<meta name="citation_publisher" content="National Center for Biotechnology Information (US)">
<meta name="citation_date" content="1999/10/13">
<meta name="citation_author" content="Laura Dean">
<meta name="citation_author" content="Johanna McEntyre">
<meta name="citation_fulltext_html_url" content="https://www.ncbi.nlm.nih.gov/books/NBK2334/">
<link rel="schema.DC" href="http://purl.org/DC/elements/1.0/">
<meta name="DC.Title" content="RNA surveillance: watching the defectives">
<meta name="DC.Type" content="Text">
<meta name="DC.Publisher" content="National Center for Biotechnology Information (US)">
<meta name="DC.Contributor" content="Laura Dean">
<meta name="DC.Contributor" content="Johanna McEntyre">
<meta name="DC.Date" content="1999/10/13">
<meta name="DC.Identifier" content="https://www.ncbi.nlm.nih.gov/books/NBK2334/">
<meta name="description" content="Only those changes in DNA sequence that have functional consequences are known as disease-causing mutations. One such frequently occurring mutation causes a premature stop codon to appear in the middle of a protein-coding sequence of messenger RNA (mRNA). Stop codons (a triplet of nucleotides: UAA, UAG, or UGA) normally signal the end of the stretch of mRNA that is translated into protein so that when one appears early, the result can be a truncated protein that could have nasty consequences for the host organism.">
<meta name="og:title" content="RNA surveillance: watching the defectives">
<meta name="og:type" content="book">
<meta name="og:description" content="Only those changes in DNA sequence that have functional consequences are known as disease-causing mutations. One such frequently occurring mutation causes a premature stop codon to appear in the middle of a protein-coding sequence of messenger RNA (mRNA). Stop codons (a triplet of nucleotides: UAA, UAG, or UGA) normally signal the end of the stretch of mRNA that is translated into protein so that when one appears early, the result can be a truncated protein that could have nasty consequences for the host organism.">
<meta name="og:url" content="https://www.ncbi.nlm.nih.gov/books/NBK2334/">
<meta name="og:site_name" content="NCBI Bookshelf">
<meta name="og:image" content="https://www.ncbi.nlm.nih.gov/corehtml/pmc/pmcgifs/bookshelf/thumbs/th-coffeebrk-lrg.png">
<meta name="twitter:card" content="summary">
<meta name="twitter:site" content="@ncbibooks">
<meta name="bk-non-canon-loc" content="/books/n/coffeebrk/A17/?report=reader">
<link rel="canonical" href="https://www.ncbi.nlm.nih.gov/books/NBK2334/">
<link href="https://fonts.googleapis.com/css?family=Archivo+Narrow:400,700,400italic,700italic&amp;subset=latin" rel="stylesheet" type="text/css">
<link rel="stylesheet" href="/corehtml/pmc/jatsreader/ptpmc_3.22/css/libs.min.css">
<link rel="stylesheet" href="/corehtml/pmc/jatsreader/ptpmc_3.22/css/jr.min.css">
<meta name="format-detection" content="telephone=no">
<link rel="stylesheet" href="/corehtml/pmc/css/bookshelf/2.26/css/books.min.css" type="text/css">
<link rel="stylesheet" href="/corehtml/pmc/css/bookshelf/2.26/css//books_print.min.css" type="text/css" media="print">
<link rel="stylesheet" href="/corehtml/pmc/css/bookshelf/2.26/css/books_reader.min.css" type="text/css">
<style type="text/css">p a.figpopup{display:inline !important} .bk_tt {font-family: monospace} .first-line-outdent .bk_ref {display: inline} .body-content h2, .body-content .h2 {border-bottom: 1px solid #97B0C8} .body-content h2.inline {border-bottom: none} a.page-toc-label , .jig-ncbismoothscroll a {text-decoration:none;border:0 !important} .temp-labeled-list .graphic {display:inline-block !important} .temp-labeled-list img{width:100%}</style>
<link rel="shortcut icon" href="//www.ncbi.nlm.nih.gov/favicon.ico">
<meta name="ncbi_phid" content="CE8B7DC87C81BD810000000000B10096.m_5">
<meta name='referrer' content='origin-when-cross-origin'/><link type="text/css" rel="stylesheet" href="//static.pubmed.gov/portal/portal3rc.fcgi/4216699/css/3852956/3849091.css"></head>
<body>
<!-- Book content! -->
<div id="jr" data-jr-path="/corehtml/pmc/jatsreader/ptpmc_3.22/"><div class="jr-unsupported"><table class="modal"><tr><td><span class="attn inline-block"></span><br />Your browser does not support the NLM PubReader view.<br />Go to <a href="/pmc/about/pr-browsers/">this page</a> to see a list of supported browsers<br />or return to the <br /><a href="/books/NBK2334/?report=classic">regular view</a>.</td></tr></table></div><div id="jr-ui" class="hidden"><nav id="jr-head"><div class="flexh tb"><div id="jr-tb1"><a id="jr-links-sw" class="hidden" title="Links"><svg xmlns="http://www.w3.org/2000/svg" version="1.1" x="0px" y="0px" viewBox="0 0 70.6 85.3" style="enable-background:new 0 0 70.6 85.3;vertical-align:middle" xml:space="preserve" width="24" height="24">
<style type="text/css">.st0{fill:#939598;}</style>
<g>
<path class="st0" d="M36,0C12.8,2.2-22.4,14.6,19.6,32.5C40.7,41.4-30.6,14,35.9,9.8"></path>
<path class="st0" d="M34.5,85.3c23.2-2.2,58.4-14.6,16.4-32.5c-21.1-8.9,50.2,18.5-16.3,22.7"></path>
<path class="st0" d="M34.7,37.1c66.5-4.2-4.8-31.6,16.3-22.7c42.1,17.9,6.9,30.3-16.4,32.5h1.7c-66.2,4.4,4.8,31.6-16.3,22.7 c-42.1-17.9-6.9-30.3,16.4-32.5"></path>
</g>
</svg> Books</a></div><div class="jr-rhead f1 flexh"><div class="head"><a href="/books/n/coffeebrk/A18/?report=reader"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M75,30 c-80,60 -80,0 0,60 c-30,-60 -30,0 0,-60"></path><text x="20" y="28" textLength="60" style="font-size:25px">Prev</text></svg></a></div><div class="body"><div class="t">RNA surveillance: watching the defectives: detecting premature stop codons in mRNA halts the production of dangerous truncated proteins</div><div class="j">Coffee Break: Tutorials for NCBI Tools [Internet]</div></div><div class="tail"><a href="/books/n/coffeebrk/A16/?report=reader"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M25,30c80,60 80,0 0,60 c30,-60 30,0 0,-60"></path><text x="20" y="28" textLength="60" style="font-size:25px">Next</text></svg></a></div></div><div id="jr-tb2"><a id="jr-bkhelp-sw" class="btn wsprkl hidden" title="Help with NLM PubReader">?</a><a id="jr-help-sw" class="btn wsprkl hidden" title="Settings and typography in NLM PubReader"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" preserveAspectRatio="none"><path d="M462,283.742v-55.485l-29.981-10.662c-11.431-4.065-20.628-12.794-25.274-24.001 c-0.002-0.004-0.004-0.009-0.006-0.013c-4.659-11.235-4.333-23.918,0.889-34.903l13.653-28.724l-39.234-39.234l-28.72,13.652 c-10.979,5.219-23.68,5.546-34.908,0.889c-0.005-0.002-0.01-0.003-0.014-0.005c-11.215-4.65-19.933-13.834-24-25.273L283.741,50 h-55.484l-10.662,29.981c-4.065,11.431-12.794,20.627-24.001,25.274c-0.005,0.002-0.009,0.004-0.014,0.005 c-11.235,4.66-23.919,4.333-34.905-0.889l-28.723-13.653l-39.234,39.234l13.653,28.721c5.219,10.979,5.545,23.681,0.889,34.91 c-0.002,0.004-0.004,0.009-0.006,0.013c-4.649,11.214-13.834,19.931-25.271,23.998L50,228.257v55.485l29.98,10.661 c11.431,4.065,20.627,12.794,25.274,24c0.002,0.005,0.003,0.01,0.005,0.014c4.66,11.236,4.334,23.921-0.888,34.906l-13.654,28.723 l39.234,39.234l28.721-13.652c10.979-5.219,23.681-5.546,34.909-0.889c0.005,0.002,0.01,0.004,0.014,0.006 c11.214,4.649,19.93,13.833,23.998,25.271L228.257,462h55.484l10.595-29.79c4.103-11.538,12.908-20.824,24.216-25.525 c0.005-0.002,0.009-0.004,0.014-0.006c11.127-4.628,23.694-4.311,34.578,0.863l28.902,13.738l39.234-39.234l-13.66-28.737 c-5.214-10.969-5.539-23.659-0.886-34.877c0.002-0.005,0.004-0.009,0.006-0.014c4.654-11.225,13.848-19.949,25.297-24.021 L462,283.742z M256,331.546c-41.724,0-75.548-33.823-75.548-75.546s33.824-75.547,75.548-75.547 c41.723,0,75.546,33.824,75.546,75.547S297.723,331.546,256,331.546z"></path></svg></a><a id="jr-fip-sw" class="btn wsprkl hidden" title="Find"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 550 600" preserveAspectRatio="none"><path fill="none" stroke="#000" stroke-width="36" stroke-linecap="round" style="fill:#FFF" d="m320,350a153,153 0 1,0-2,2l170,170m-91-117 110,110-26,26-110-110"></path></svg></a><a id="jr-rtoc-sw" class="btn wsprkl hidden" title="Table of Contents"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M20,20h10v8H20V20zM36,20h44v8H36V20zM20,37.33h10v8H20V37.33zM36,37.33h44v8H36V37.33zM20,54.66h10v8H20V54.66zM36,54.66h44v8H36V54.66zM20,72h10v8 H20V72zM36,72h44v8H36V72z"></path></svg></a></div></div></nav><nav id="jr-dash" class="noselect"><nav id="jr-dash" class="noselect"><div id="jr-pi" class="hidden"><a id="jr-pi-prev" class="hidden" title="Previous page"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M75,30 c-80,60 -80,0 0,60 c-30,-60 -30,0 0,-60"></path><text x="20" y="28" textLength="60" style="font-size:25px">Prev</text></svg></a><div class="pginfo">Page <i class="jr-pg-pn">0</i> of <i class="jr-pg-lp">0</i></div><a id="jr-pi-next" class="hidden" title="Next page"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M25,30c80,60 80,0 0,60 c30,-60 30,0 0,-60"></path><text x="20" y="28" textLength="60" style="font-size:25px">Next</text></svg></a></div><div id="jr-is-tb"><a id="jr-is-sw" class="btn wsprkl hidden" title="Switch between Figures/Tables strip and Progress bar"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><rect x="10" y="40" width="20" height="20"></rect><rect x="40" y="40" width="20" height="20"></rect><rect x="70" y="40" width="20" height="20"></rect></svg></a></div><nav id="jr-istrip" class="istrip hidden"><a id="jr-is-prev" href="#" class="hidden" title="Previous"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M80,40 60,65 80,90 70,90 50,65 70,40z M50,40 30,65 50,90 40,90 20,65 40,40z"></path><text x="35" y="25" textLength="60" style="font-size:25px">Prev</text></svg></a><a id="jr-is-next" href="#" class="hidden" title="Next"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M20,40 40,65 20,90 30,90 50,65 30,40z M50,40 70,65 50,90 60,90 80,65 60,40z"></path><text x="15" y="25" textLength="60" style="font-size:25px">Next</text></svg></a></nav><nav id="jr-progress"></nav></nav></nav><aside id="jr-links-p" class="hidden flexv"><div class="tb sk-htbar flexh"><div><a class="jr-p-close btn wsprkl">Done</a></div><div class="title-text f1">NCBI Bookshelf</div></div><div class="cnt lol f1"><a href="/books/">Home</a><a href="/books/browse/">Browse All Titles</a><a class="btn share" target="_blank" rel="noopener noreferrer" href="https://www.facebook.com/sharer/sharer.php?u=https://www.ncbi.nlm.nih.gov/books/NBK2334/"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 33 33" style="vertical-align:middle" width="24" height="24" preserveAspectRatio="none"><g><path d="M 17.996,32L 12,32 L 12,16 l-4,0 l0-5.514 l 4-0.002l-0.006-3.248C 11.993,2.737, 13.213,0, 18.512,0l 4.412,0 l0,5.515 l-2.757,0 c-2.063,0-2.163,0.77-2.163,2.209l-0.008,2.76l 4.959,0 l-0.585,5.514L 18,16L 17.996,32z"></path></g></svg> Share on Facebook</a><a class="btn share" target="_blank" rel="noopener noreferrer" href="https://twitter.com/intent/tweet?url=https://www.ncbi.nlm.nih.gov/books/NBK2334/&amp;text=RNA%20surveillance%3A%20watching%20the%20defectives"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 33 33" style="vertical-align:middle" width="24" height="24"><g><path d="M 32,6.076c-1.177,0.522-2.443,0.875-3.771,1.034c 1.355-0.813, 2.396-2.099, 2.887-3.632 c-1.269,0.752-2.674,1.299-4.169,1.593c-1.198-1.276-2.904-2.073-4.792-2.073c-3.626,0-6.565,2.939-6.565,6.565 c0,0.515, 0.058,1.016, 0.17,1.496c-5.456-0.274-10.294-2.888-13.532-6.86c-0.565,0.97-0.889,2.097-0.889,3.301 c0,2.278, 1.159,4.287, 2.921,5.465c-1.076-0.034-2.088-0.329-2.974-0.821c-0.001,0.027-0.001,0.055-0.001,0.083 c0,3.181, 2.263,5.834, 5.266,6.438c-0.551,0.15-1.131,0.23-1.73,0.23c-0.423,0-0.834-0.041-1.235-0.118 c 0.836,2.608, 3.26,4.506, 6.133,4.559c-2.247,1.761-5.078,2.81-8.154,2.81c-0.53,0-1.052-0.031-1.566-0.092 c 2.905,1.863, 6.356,2.95, 10.064,2.95c 12.076,0, 18.679-10.004, 18.679-18.68c0-0.285-0.006-0.568-0.019-0.849 C 30.007,8.548, 31.12,7.392, 32,6.076z"></path></g></svg> Share on Twitter</a></div></aside><aside id="jr-rtoc-p" class="hidden flexv"><div class="tb sk-htbar flexh"><div><a class="jr-p-close btn wsprkl">Done</a></div><div class="title-text f1">Table of Content</div></div><div class="cnt lol f1"><a href="/books/n/coffeebrk/?report=reader">Title Information</a><a href="/books/n/coffeebrk/toc/?report=reader">Table of Contents Page</a></div></aside><aside id="jr-help-p" class="hidden flexv"><div class="tb sk-htbar flexh"><div><a class="jr-p-close btn wsprkl">Done</a></div><div class="title-text f1">Settings</div></div><div class="cnt f1"><div id="jr-typo-p" class="typo"><div><a class="sf btn wsprkl">A-</a><a class="lf btn wsprkl">A+</a></div><div><a class="bcol-auto btn wsprkl"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200 100" preserveAspectRatio="none"><text x="10" y="70" style="font-size:60px;font-family: Trebuchet MS, ArialMT, Arial, sans-serif" textLength="180">AUTO</text></svg></a><a class="bcol-1 btn wsprkl"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M15,25 85,25zM15,40 85,40zM15,55 85,55zM15,70 85,70z"></path></svg></a><a class="bcol-2 btn wsprkl"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M5,25 45,25z M55,25 95,25zM5,40 45,40z M55,40 95,40zM5,55 45,55z M55,55 95,55zM5,70 45,70z M55,70 95,70z"></path></svg></a></div></div><div class="lol"><a class="" href="/books/NBK2334/?report=classic">Switch to classic view</a><a href="/books/NBK2334/pdf/Bookshelf_NBK2334.pdf">PDF (90K)</a><a href="/books/n/coffeebrk/pdf/">PDF (3.7M)</a><a href="/books/NBK2334/?report=printable">Print View</a></div></div></aside><aside id="jr-bkhelp-p" class="hidden flexv"><div class="tb sk-htbar flexh"><div><a class="jr-p-close btn wsprkl">Done</a></div><div class="title-text f1">Help</div></div><div class="cnt f1 lol"><a id="jr-helpobj-sw" data-path="/corehtml/pmc/jatsreader/ptpmc_3.22/" data-href="/corehtml/pmc/jatsreader/ptpmc_3.22/img/bookshelf/help.xml" href="">Help</a><a href="mailto:info@ncbi.nlm.nih.gov?subject=PubReader%20feedback%20%2F%20NBK2334%20%2F%20sid%3ACE8B5AF87C7FFCB1_0191SID%20%2F%20phid%3ACE8B7DC87C81BD810000000000B10096.4">Send us feedback</a><a id="jr-about-sw" data-path="/corehtml/pmc/jatsreader/ptpmc_3.22/" data-href="/corehtml/pmc/jatsreader/ptpmc_3.22/img/bookshelf/about.xml" href="">About PubReader</a></div></aside><aside id="jr-objectbox" class="thidden hidden"><div class="jr-objectbox-close wsprkl">&#10008;</div><div class="jr-objectbox-inner cnt"><div class="jr-objectbox-drawer"></div></div></aside><nav id="jr-pm-left" class="hidden"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 800" preserveAspectRatio="none"><text font-stretch="ultra-condensed" x="800" y="-15" text-anchor="end" transform="rotate(90)" font-size="18" letter-spacing=".1em">Previous Page</text></svg></nav><nav id="jr-pm-right" class="hidden"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 800" preserveAspectRatio="none"><text font-stretch="ultra-condensed" x="800" y="-15" text-anchor="end" transform="rotate(90)" font-size="18" letter-spacing=".1em">Next Page</text></svg></nav><nav id="jr-fip" class="hidden"><nav id="jr-fip-term-p"><input type="search" placeholder="search this page" id="jr-fip-term" autocorrect="off" autocomplete="off" /><a id="jr-fip-mg" class="wsprkl btn" title="Find"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 550 600" preserveAspectRatio="none"><path fill="none" stroke="#000" stroke-width="36" stroke-linecap="round" style="fill:#FFF" d="m320,350a153,153 0 1,0-2,2l170,170m-91-117 110,110-26,26-110-110"></path></svg></a><a id="jr-fip-done" class="wsprkl btn" title="Dismiss find">&#10008;</a></nav><nav id="jr-fip-info-p"><a id="jr-fip-prev" class="wsprkl btn" title="Jump to previuos match">&#9664;</a><button id="jr-fip-matches">no matches yet</button><a id="jr-fip-next" class="wsprkl btn" title="Jump to next match">&#9654;</a></nav></nav></div><div id="jr-epub-interstitial" class="hidden"></div><div id="jr-content"><article data-type="main"><div class="main-content lit-style" itemscope="itemscope" itemtype="http://schema.org/CreativeWork"><div class="meta-content fm-sec"><div class="fm-sec"><h1 id="_NBK2334_"><span class="title" itemprop="name">RNA surveillance: watching the defectives</span></h1><div class="subtitle">detecting premature stop codons in mRNA halts the production of dangerous truncated proteins</div><p class="fm-aai"><a href="#_NBK2334_pubdet_">Publication Details</a></p></div></div><div class="body-content whole_rhythm" itemprop="text"><p>Only those changes in DNA sequence that have functional consequences are known as disease-causing mutations. One such frequently occurring mutation causes a premature stop codon to appear in the middle of a protein-coding sequence of messenger RNA (mRNA). Stop codons (a triplet of nucleotides: UAA, UAG, or UGA) normally signal the end of the stretch of mRNA that is translated into protein so that when one appears early, the result can be a truncated protein that could have nasty consequences for the host organism.</p><p>However, a mechanism known as "nonsense-mediated decay" has evolved to detect these harmful RNAs, and <u>sequence analysis</u> suggests that it may have been conserved in eukaryotic organisms, including <a href="/genemap/map.cgi?MAP=GB4&#x00026;BIN=562&#x00026;MARK=A006H36" ref="pagearea=body&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">humans</a>. In yeast, three proteins have been identified that are required to seek and destroy the partly translated RNAs: <a href="/pubmed?term=Upf1p" ref="pagearea=body&amp;targetsite=entrez&amp;targetcat=term&amp;targettype=pubmed"><u>Upf1p</u></a>, Upf2p, and Upf3p.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figA642" co-legend-rid="figlgndA642"><a href="/books/NBK2334/figure/A642/?report=objectonly" target="object" title="Figure" class="img_link icnblk_img figpopup" rid-figpopup="figA642" rid-ob="figobA642"><img class="small-thumb" src="/books/NBK2334/bin/cb07_big.gif" src-large="/books/NBK2334/bin/cb07_big.jpg" alt="Nonsense-mediated decay (NMD) in yeast, as a model for NMD in humans." /></a><div class="icnblk_cntnt" id="figlgndA642"><h4 id="A642"><a href="/books/NBK2334/figure/A642/?report=objectonly" target="object" rid-ob="figobA642">Figure</a></h4><p class="float-caption no_bottom_margin">Nonsense-mediated decay (NMD) in yeast, as a model for NMD in humans. Ribonuclear proteins that bind to mRNAs in the nucleus remain associated with the mRNA as it becomes attached to the ribosome. When a premature stop codon is present, one of these <a href="/books/NBK2334/figure/A642/?report=objectonly" target="object" rid-ob="figobA642">(more...)</a></p></div></div><p>Upf1p is an RNA unwinding enzyme, a helicase, that requires ATP for activity. Unfortunately, Upf1p will unwind pretty much anything, not just the problem mRNAs. So Upf2p and Upf3p are thought to be required to help Upf1p discriminate between nonsense and "real" mRNAs.</p><p>How do the core proteins work in synergy to trigger <a href="/pubmed?term=nonsense-mediated%20decay" ref="pagearea=body&amp;targetsite=entrez&amp;targetcat=term&amp;targettype=pubmed">nonsense-mediated decay?</a> One possibility is that Upf3p, along with several other ribonuclear proteins, may first bind to an mRNA as it is being exported from the nucleus en route to the ribosome, the site of protein synthesis. If the mRNA is fully translated into protein, Upf3p and the other protein factors are displaced. However, if there is a premature stop codon, Upf3p and cohorts may sit tight and mark the mutant mRNA as one that needs to be disposed of.</p><p>Experiments have shown that Upf3p can bind Upf2p. Once bound, Upf2p could signal to the "termination complex", a mixed bag of termination factors that includes Upf1p. This results in the release of the incomplete polypeptide from the ribosome, mRNA unwinding by Upf1p and, exposure of the mRNA for total degradation by exonuclease.</p><p>Although this model is attractive, more experiments are required to show that this actually happens in a living yeast cell.</p><p>Many of the mutations that form a <a href="/pubmed?term=premature%20stop%20codon%20AND%20disease" ref="pagearea=body&amp;targetsite=entrez&amp;targetcat=term&amp;targettype=pubmed">premature stop codon lead to human disease</a>, for example, those in <i>BRCA1</i> that lead to breast cancer, or those in <i>NF1</i> that lead to neurofibromatosis type 1, to name just two. There are two ways by which nonsense-mediated decay can play a role in <a href="/entrez/dispomim.cgi?id=601430" ref="pagearea=body&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">the disease process</a>. The first occurs when the machinery is functioning correctly: if mutant mRNAs are removed, then there will be a reduction in the amount of mRNA and protein available in the cell. The second is when a mutation occurs in the nonsense-mediated decay process itself, such as a mutation in <a href="/omim/601430" ref="pagearea=body&amp;targetsite=entrez&amp;targetcat=term&amp;targettype=omim">RENT1</a>, a human homolog of Upf1p, resulting in a population of truncated proteins, which could be harmful when targeted to their site of function.
</p><p>
</p><div id="A320" class="box boxed-text-box whole_rhythm hide-overflow"><h3><span class="title">Use BLAST to search for relatives of yeast Upf1p</span></h3><p>Created: October 13, 1999</p><p>Click on the link below to start an html tutorial.</p><p>Find relatives of yeast Upf1p</p></div><div id="bk_toc_contnr"></div></div></div><div class="fm-sec"><h2 id="_NBK2334_pubdet_">Publication Details</h2><h3>Publication History</h3><p class="small">Created: <span itemprop="datePublished">October 13, 1999</span>.</p><h3>Copyright</h3><div><div class="half_rhythm"><a href="/books/about/copyright/">Copyright Notice</a></div></div><h3>Publisher</h3><p><a href="http://www.ncbi.nlm.nih.gov/" ref="pagearea=page-banner&amp;targetsite=external&amp;targetcat=link&amp;targettype=publisher">National Center for Biotechnology Information (US)</a>, Bethesda (MD)</p><h3>NLM Citation</h3><p>Dean L, McEntyre J, editors. Coffee Break: Tutorials for NCBI Tools [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 1999-. RNA surveillance: watching the defectives: detecting premature stop codons in mRNA halts the production of dangerous truncated proteins. 1999 Oct 13.<span class="bk_cite_avail"></span></p></div><div class="small-screen-prev"><a href="/books/n/coffeebrk/A18/?report=reader"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M75,30 c-80,60 -80,0 0,60 c-30,-60 -30,0 0,-60"></path><text x="20" y="28" textLength="60" style="font-size:25px">Prev</text></svg></a></div><div class="small-screen-next"><a href="/books/n/coffeebrk/A16/?report=reader"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" preserveAspectRatio="none"><path d="M25,30c80,60 80,0 0,60 c30,-60 30,0 0,-60"></path><text x="20" y="28" textLength="60" style="font-size:25px">Next</text></svg></a></div></article><article data-type="fig" id="figobA642"><div id="A642" class="figure bk_fig"><div class="graphic"><img data-src="/books/NBK2334/bin/cb07_big.jpg" alt="Nonsense-mediated decay (NMD) in yeast, as a model for NMD in humans." /></div><h3><span class="title">Nonsense-mediated decay (NMD) in yeast, as a model for NMD in humans</span></h3><div class="caption"><p><br />Ribonuclear proteins that bind to mRNAs in the nucleus remain associated with the mRNA as it becomes attached to the ribosome. When a premature stop codon is present, one of these proteins could be Upf3p. If Upf3p, or another as yet unidentified factor, is recognized by the surveillance complex (represented here by the eye), then the NMD mechanism is triggered. In yeast, this trigger may be assisted by the binding of Upf2p to Upf3p, after which the Upf1p helicase unwinds the mRNA, leaving it open for degradation by a decapping enzyme and exonuclease. Should the premature stop codon not be recognized, translation of the mRNA proceeds and results in the production of a truncated protein.</p></div></div></article><article data-type="boxed-text" id="figobA320"><div id="A320" class="box boxed-text-box whole_rhythm hide-overflow"><h3><span class="title">Use BLAST to search for relatives of yeast Upf1p</span></h3><p>Created: October 13, 1999</p><p>Click on the link below to start an html tutorial.</p><p>Find relatives of yeast Upf1p</p></div></article></div><div id="jr-scripts"><script src="/corehtml/pmc/jatsreader/ptpmc_3.22/js/libs.min.js"> </script><script src="/corehtml/pmc/jatsreader/ptpmc_3.22/js/jr.min.js"> </script></div></div>
<!-- Book content -->
<script type="text/javascript" src="/portal/portal3rc.fcgi/rlib/js/InstrumentNCBIBaseJS/InstrumentPageStarterJS.js"> </script>
<!-- CE8B5AF87C7FFCB1_0191SID /projects/books/PBooks@9.11 portal104 v4.1.r689238 Tue, Oct 22 2024 16:10:51 -->
<span id="portal-csrf-token" style="display:none" data-token="CE8B5AF87C7FFCB1_0191SID"></span>
<script type="text/javascript" src="//static.pubmed.gov/portal/portal3rc.fcgi/4216699/js/3968615.js" snapshot="books"></script></body>
</html>