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<br>
<img height="33" width="178" src="images/issue.gif" alt="In this issue..."><br>
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<span class="navon">Model Maker</span><br>
<br>
<a href="virus.html" class="navoff">Virus Reference<br>
Sequences</a><br>
<br>
<a href="virus.html" class="navoff">Release of the<br>
1,000th Virus<br>
Reference Genome</a><br>
<br>
<a href="mapviewer.html" class="navoff">New MapViewer<br>
Displays</a><br>
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<a href="mapviewer.html" class="navoff">Other Genomic<br>
MapViews</a><br>
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<a href="mouse.html" class="navoff">Mouse Genome<br>
BLAST</a><br>
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in GenBank</a><br>
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<a href="organism.html" class="navoff">Organism-Specific<br>
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<a href="barbara.html" class="navoff">Barbara Rapp<br>
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<p><img height="25" width="8" src="images/dotclear.gif" alt=" "><br>
<span class="headlines"><b class="headlines">Make Your Own Gene Models
with Model Maker</b></span></p>
<br>
<span class="bodycopy">The Model Maker is a tool that allows the construction
of an mRNA sequence model using putative exons defined by <i>ab initio</i>
prediction and by aligning GenBank&reg; transcripts (including ESTs)
and NCBI RefSeqs to the NCBI human genome assembly. The ability to generate
alternative transcript models using novel combinations of exons not
represented in any single mRNA sequence alignment is useful in the exploration
of gene model variants.<br>
</span> <span class="bodycopy"> <br>
To generate a Model Maker display centered on a gene of interest, go
to the Human Map Viewer page (Model Maker links will soon be available
directly from LocusLink) and type the gene symbol or gene name into
the query box. Select the Genes_seq map as the Master Map and click
on the &#147;mm&#148; link to the right of the gene name. The Model
Maker display for the HOXB1 gene is shown in Figure 1 below. The gene
is found on the RefSeq contig NT_010783.9, with the chromosome coordinates
shown. You may move upstream or downstream from the contig using a pair
of horizontal arrows. If you click on the sequence viewer link &#147;sv&#148;
after this repositioning, you will be able to see the upstream or downstream
sequences of the contig. <br>
<br>
</span> <span class="bodycopy"> The Model Maker page is divided into
several sections. The first section displays &#147;evidence&#148; for
exons in the form of sequence records from the databases that have been
aligned to human genome assembly contig NT_010783.9 to produce the NCBI
gene model for HOXB1. These sequences include, from top to bottom, a
GenBank mRNA sequence and the mRNA RefSeq derived from it, each contributing
2 exons; a GenomeScan-generated model, contributing an additional small
exon; and a genomic RefSeq derived from the alignment of the mRNA RefSeq
with the contig, contributing 2 exons.<br>
<br>
The Model Maker gathers the unique putative exons from the various alignments
used as evidence, assigns each a consecutive number, and presents them
in a &#147;graphic view&#148;. In the Figure, three unique exons are
shown in the &#147;graphic view&#148; which may be added or removed
from the nascent model by clicking them on or off. By choosing the &#147;hits&#148;
hyperlink next to an evidence sequence, the coordinates of BLAST&reg;
hits for the evidence sequence on the human genomic sequence are shown
and intron lengths may be deduced. It is also possible to select whole
&#147;exon sets&#148; from evidence mRNAs, using the &#147;set&#148;
link, add EST alignments to the evidence list, extend the region shown
downstream and upstream or switch to the opposite strand.<br>
</span><br>
<a href="#" onClick="MM_openBrWindow('model_lrg.html','Figure','scrollbars=yes,width=580,height=523')"><img src="images/model_sm.gif" width="420" height="373" border="1" alt=""><br></a>
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<a href="#" onClick="MM_openBrWindow('model_lrg.html','Figure','scrollbars=yes,width=580,height=523')"><br>
</a><span class="captions">Figure 1:&nbsp;</span><span class="captions2">Model
Maker display for HOX1B located on contig NT_010783.9. Access the Contig
record by clicking the Accession Number hyperlink NT_010783.9. Move upstream
or downstream by clicking on the arrows: &lt;&lt;&lt; (upstream) or &gt;&gt;&gt;
(downstream). View the opposite strand by clicking on &#147;change strand&#148;
hyperlink. Select &#147;set&#148; to select an evidence record as your
model. Select &#147;add ESTs&#148; to add a graphical display of ESTs.
To build a custom model, select the exon or EST of interest by clicking
on the graphic view segment or select the exon from the table by using
a check box. Monitor the growing model by viewing its translation in three
different reading frames. The longest ORF in each frame is denoted by
UPPERCASE letters. Save your results by clicking on the &#147;Save&#148;
hyperlink.</span><br>
<br>
<span class="bodycopy"> The information in the &#147;graphic view&#148;
is also presented as a &#147;table view&#148; that gives the start and
stop positions of each putative exon, along with the first three and
last three bases of each exon and two bases immediately upstream and
downstream of the exon. Exons are selected for inclusion in the model
using check boxes. Numbered links at the ends of each exon facilitate
the selection of adjacent exons implied by existing transcripts. As
each exon is selected, the 3- frame trans-lations of the model sequence
are updated in the ORF Frames boxes. The longest ORF in each translation
is shown in UPPER CASE letters. As compatible exons are added to the
model, in phase, an ORF in at least one of the three reading-frames
lengthens. When the stop codon is reached and the model is complete,
it may be saved to a local file in FASTA format for use with other programs.&nbsp;</span><span class="authors">&#151;EP,
MB</span><span class="bodycopy"><br>
</span><br>
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