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| Identifier |
000376303 |
| Title |
Στόχευση προπρωτεϊνών στην μεμβράνη με την βοήθεια σαπερονών |
| Alternative Title |
Chaperone assisted preprotein targeting to the membrane |
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Author
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Φαμέλης, Νικόλαος Γεωρ.
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Reviewer
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Περγαντής, Σπύρος
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Thesis advisor
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Οικονόμου, Αναστάσιος
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| Abstract |
In this thesis we studied preprotein targeting to the membrane in the presence of chaperones using size exclusion chromatography coupled online with MALLS/QELS. Using alkaline phosphatase and b-glycosidase as substrates we studied under which conditions they bind chaperones SecB and TF. Only the molten globule state of the alkaline phosphatase was able to interact with chaperones. The recognition sites on the preprotein were different for TF and SecB. Interactions between mature alkaline phosphatase and TF are not strong enough to form a stable complex unless signal peptide is present. From the other hand translocation-specific chaperone SecB can form stable complex with the substrate even in the absence of signal peptide. It seems that the specificity of the interaction with SecB is implicated in the mature region of alkaline phosphatase. In case of b-glycosidase as a substrate, both chaperones prevent aggregates formation while only interactions with SecB lead to the formation of a stable complex. Furthermore we have shown that SecB has two independent roles at the Sec pathway. Its key role is the allosteric activation of SecA upon binding, which is necessary and sufficient for the substrate secretion. Its supporting part involves its chaperone activity, that is to maintain preproteins at a translocation-competent state (non-native state). Thus we propose a mechanism for preprotein targeting to the membrane that involves direct docking to the ATPase rather than chaperone mediated delivery.
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| Language |
Greek |
| Subject |
Chaperones |
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Preproteins |
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Προπρωτεΐνες |
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Σαπερόνες |
| Issue date |
2012-11-16 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
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Type of Work--Post-graduate theses
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| Views |
239 |
Στόχευση προπρωτεϊνών στην μεμβράνη με την βοήθεια σαπερονών
