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| {{STRUCTURE_2p8x| PDB=2p8x | SCENE= }} | | {{STRUCTURE_2p8x| PDB=2p8x | SCENE= }} |
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| '''Fitted structure of ADPR-eEF2 in the 80S:ADPR-eEF2:GDPNP cryo-EM reconstruction'''
| | ===Fitted structure of ADPR-eEF2 in the 80S:ADPR-eEF2:GDPNP cryo-EM reconstruction=== |
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| ==Overview==
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| On the basis of kinetic data on ribosome protein synthesis, the mechanical energy for translocation of the mRNA-tRNA complex is thought to be provided by GTP hydrolysis of an elongation factor (eEF2 in eukaryotes, EF-G in bacteria). We have obtained cryo-EM reconstructions of eukaryotic ribosomes complexed with ADP-ribosylated eEF2 (ADPR-eEF2), before and after GTP hydrolysis, providing a structural basis for analyzing the GTPase-coupled mechanism of translocation. Using the ADP-ribosyl group as a distinct marker, we observe conformational changes of ADPR-eEF2 that are due strictly to GTP hydrolysis. These movements are likely representative of native eEF2 motions in a physiological context and are sufficient to uncouple the mRNA-tRNA complex from two universally conserved bases in the ribosomal decoding center (A1492 and A1493 in Escherichia coli) during translocation. Interpretation of these data provides a detailed two-step model of translocation that begins with the eEF2/EF-G binding-induced ratcheting motion of the small ribosomal subunit. GTP hydrolysis then uncouples the mRNA-tRNA complex from the decoding center so translocation of the mRNA-tRNA moiety may be completed by a head rotation of the small subunit.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17446867}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17446867 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17446867}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Gtpase]] | | [[Category: Gtpase]] |
| [[Category: Translocation]] | | [[Category: Translocation]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 12:37:43 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 08:01:50 2008'' |
