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Media type:
E-Article
Title:
Inactivation of Cap-Binding Proteins Accompanies the Shut-Off of Host Protein Synthesis by Poliovirus
Contributor:
Sonenberg, Nahum
Published:
National Academy of Sciences of the United States of America, 1982
Published in:
Proceedings of the National Academy of Sciences of the United States of America, 79 (1982) 11, Seite 3447-3451
Language:
English
ISSN:
0027-8424
Origination:
Footnote:
Description:
<p>Infection of HeLa cells with poliovirus results in a rapid shut-off of host protein synthesis. It has been suggested that inactivation of a protein that binds to the cap structure of cellular mRNAs would explain the selective inhibition of host protein synthesis because the naturally uncapped poliovirus RNA can be translated by a cap-independent mechanism. To test directly for the presence of cap-binding proteins in poliovirus-infected and mock-infected cells, we analyzed initiation factor preparations for their ability to specifically crosslink to the 5<sup>′</sup>cap structure of oxidized reovirus mRNA. The data presented here show that the crosslinking ability of the different cap-binding proteins (24-, 28-, 32-, 50-, and 80-kilodalton polypeptides) is reduced in preparations from poliovirus-infected as compared to mock-infected cells. This reduction correlates with the inability of initiation factor preparations from infected cells to restore translation of capped mRNAs in extracts of poliovirus-infected cells. In addition, initiation factor preparations from poliovirus-infected cells have the ability to rapidly inactivate cap-binding proteins and can also impair the restoring activity of initiation factors from mock-infected cells.</p>