Ubiquitin- and ATP-independent proteolytic turnover of p21 by the REGr-proteasome pathway (Mol Cell, 2007, 26:831-842)

報告日期: 2007/09/28
報告時間: 15:10/16:00
報告學生: 黃怡璇
講評老師: 曾大千


Ubiquitin- and ATP- Independent Proteolytic Turnover of p21 by the

REGg-Proteasome Pathway


Speaker     黃怡璇 

Commentator曾大千 老師 

Date2007/09/28 , 15:10~16:00 pm

PlaceRoom 602


Previous discovery indicated that the REGg, was a proteasome activator directed degradation of the steroid receptor coactivator SRC-3 by the 20S proteasome in an ATP and ubiquitin-independent manner. In other studies that characterized REGg-mediated turnover of SRC-3 and the hepatitis C virus core protein. By using a combination of 2D electrophoresis and mass spectrometry, authors discovered that p21Waf/Cip1 is another important REGg target protein. In this study, the REGg antibody can successfully coimmunoprecipitate p21 indicating that p21 and REGg can directly interact with each other. Authors confirmed that the REGg-mediated regulation of p21 is due to accelerated degradation of the p21 protein. Experiment shows that REGg-dependent protein degradation by the 20S core proteasome does not require ATP and ubiquitin-activating enzyme. P21 occupies a central position in the regulation of the cell cycle in many tissues. Previous reports that endogenous p21 has been known to interact with many different proteins such as CDK2/cyclin complexes. Authors confirm that REGg interacts preferentially with unbound p21 and REGg proteasome mainly targets free p21 for degradation. The REGg alteration on the cell cycle was due to REGg’s influence on p21.Results suggest that REGg plays a major cell-specific and ubiquitin independent role in regulating proteasomal turnover of key cellular growth control proteins.




1. Xiaotao Li, Larbi Amazit, Weiwen Long, David M. Lonard, John J. Monaco, and Bert W. O’Malley. Ubiquitin-and ATP-independent proteolytic turnover of p21 by the REGg-proteasome pathway. Molecular Cell. 2007. 26 : 831-842.


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