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| [[Image:2i46.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_2i46| PDB=2i46 | SCENE= }} | | {{STRUCTURE_2i46| PDB=2i46 | SCENE= }} |
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| '''Crystal structure of human TPP1'''
| | ===Crystal structure of human TPP1=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17237768}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17237768 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17237768}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Pot1 binding]] | | [[Category: Pot1 binding]] |
| [[Category: Tpp1]] | | [[Category: Tpp1]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 07:02:44 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 08:51:58 2008'' |
