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New page: left|200px<br /> <applet load="2i46" size="450" color="white" frame="true" align="right" spinBox="true" caption="2i46, resolution 2.7Å" /> '''Crystal structure of...
 
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[[Image:2i46.gif|left|200px]]<br />
<applet load="2i46" size="450" color="white" frame="true" align="right" spinBox="true"
caption="2i46, resolution 2.7&Aring;" />
'''Crystal structure of human TPP1'''<br />


==Overview==
==Crystal structure of human TPP1==
Telomeres were originally defined as chromosome caps that prevent the, natural ends of linear chromosomes from undergoing deleterious degradation, and fusion events. POT1 (protection of telomeres) protein binds the, single-stranded G-rich DNA overhangs at human chromosome ends and, suppresses unwanted DNA repair activities. TPP1 is a previously identified, binding partner of POT1 that has been proposed to form part of a, six-protein shelterin complex at telomeres. Here, the crystal structure of, a domain of human TPP1 reveals an oligonucleotide/oligosaccharide-binding, fold that is structurally similar to the beta-subunit of the telomere, end-binding protein of a ciliated protozoan, suggesting that TPP1 is the, missing beta-subunit of human POT1 protein. Telomeric DNA end-binding, proteins have generally been found to inhibit rather than stimulate the, action of the chromosome end-replicating enzyme, telomerase. In contrast, we find that TPP1 and POT1 form a complex with telomeric DNA that, increases the activity and processivity of the human telomerase core, enzyme. We propose that POT1-TPP1 switches from inhibiting telomerase, access to the telomere, as a component of shelterin, to serving as a, processivity factor for telomerase during telomere extension.
<StructureSection load='2i46' size='340' side='right'caption='[[2i46]], [[Resolution|resolution]] 2.70&Aring;' scene=''>
 
== Structural highlights ==
==About this Structure==
<table><tr><td colspan='2'>[[2i46]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2I46 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2I46 FirstGlance]. <br>
2I46 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2I46 OCA].  
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.7&#8491;</td></tr>
 
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2i46 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2i46 OCA], [https://pdbe.org/2i46 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2i46 RCSB], [https://www.ebi.ac.uk/pdbsum/2i46 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2i46 ProSAT]</span></td></tr>
==Reference==
</table>
The POT1-TPP1 telomere complex is a telomerase processivity factor., Wang F, Podell ER, Zaug AJ, Yang Y, Baciu P, Cech TR, Lei M, Nature. 2007 Feb 1;445(7127):506-10. Epub 2007 Jan 21. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17237768 17237768]
== Function ==
[https://www.uniprot.org/uniprot/ACD_HUMAN ACD_HUMAN] Component of the shelterin complex (telosome) that is involved in the regulation of telomere length and protection. Shelterin associates with arrays of double-stranded TTAGGG repeats added by telomerase and protects chromosome ends; without its protective activity, telomeres are no longer hidden from the DNA damage surveillance and chromosome ends are inappropriately processed by DNA repair pathways. Promotes binding of POT1 to single-stranded telomeric DNA. Modulates the inhibitory effects of POT1 on telomere elongation. The ACD-POT1 heterodimer enhances telomere elongation by increasing telomerase processivity. Plays a role in shelterin complex assembly. May play a role in organogenesis.<ref>PMID:15181449</ref> <ref>PMID:16166375</ref> <ref>PMID:16880378</ref> <ref>PMID:20231318</ref> <ref>PMID:17237768</ref>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Baciu, P.]]
[[Category: Baciu P]]
[[Category: Cech, T.R.]]
[[Category: Cech TR]]
[[Category: Else, T.]]
[[Category: Else T]]
[[Category: Hammer, G.D.]]
[[Category: Hammer GD]]
[[Category: Lei, M.]]
[[Category: Lei M]]
[[Category: Podell, E.R.]]
[[Category: Podell ER]]
[[Category: Wang, F.]]
[[Category: Wang F]]
[[Category: Yang, Y.T.]]
[[Category: Yang YT]]
[[Category: Zaug, A.J.]]
[[Category: Zaug AJ]]
[[Category: ob fold]]
[[Category: pot1 binding]]
[[Category: tpp1]]
 
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