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Updated: May 17, 2026

Ubiquitin Chain Analysis by Parallel Reaction Monitoring
Published on: June 17, 2020
The lysine48-based polyubiquitin chain proteasomal signal: not a single child anymore
Yelena Kravtsova-Ivantsiv1, Thomas Sommer, Aaron Ciechanover
1Cancer and Vascular Biology Research Center, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel. yelenaiv@tx.technion.ac.il
Abstract:
The conjugation of ubiquitin (Ub) to proteins is involved in the regulation of many processes. The modification serves as a recognition element in trans, in which downstream effectors bind to the modified protein and determine its fate and/or function. A polyUb chain that is linked through internal lysine (Lys)-48 of Ub and anchored to an internal Lys residue of the substrate has become the accepted "canonical" signal for proteasomal targeting and degradation. However, recent studies show that the signal is far more diverse and that chains based on other internal linkages, as well as linear or heterologous chains made of Ub and Ub-like proteins and even monoUb, are recognized by the proteasome. In addition, chains linked to residues other than internal Lys were described, all challenging the current paradigm.
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