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Published September 22, 2000 | public
Journal Article

Detecting and Measuring Cotranslational Protein Degradation in Vivo


Nascent polypeptides emerging from the ribosome and not yet folded may at least transiently present degradation signals similar to those recognized by the ubiquitin system in misfolded proteins. The ubiquitin sandwich technique was used to detect and measure cotranslational protein degradation in living cells. More than 50 percent of nascent protein molecules bearing an amino-terminal degradation signal can be degraded cotranslationally, never reaching their mature size before their destruction by processive proteolysis. Thus, the folding of nascent proteins, including abnormal ones, may be in kinetic competition with pathways that target these proteins for degradation cotranslationally.

Additional Information

© 2000 American Association for the Advancement of Science. Received 15 March 2000; accepted 31 July 2000. We thank F. Lévy and N. Johnsson for their contributions to early stages of this work and R. Deshaies, T. Iverson, T.-M. Yi, and members of the Varshavsky laboratory for helpful discussions and comments on the manuscript. This study was supported by a grant to A.V. from NIH. G.T. was supported in part by Amgen.

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