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Updated: Dec 25, 2025

In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones
Published on: July 25, 2019
Ubiquitin Linkage Specificity of Deubiquitinases Determines Cyclophilin Nuclear Localization and Degradation
Yanchang Li1, Qiuyan Lan2, Yuan Gao1
1State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Research Unit of Proteomics & Research and Development of New Drug of Chinese Academy of Medical Sciences, Beijing Institute of Lifeomics, 38 Science Park Road, Beijing 102206, China.
Abstract:
Ubiquitin chain specificity has been described for some deubiquitinases (DUBs) but lacks a comprehensive profiling in vivo. We used quantitative proteomics to compare the seven lysine-linked ubiquitin chains between wild-type yeast and its 20 DUB-deletion strains, which may reflect the linkage specificity of DUBs in vivo. Utilizing the specificity and ubiquitination heterogeneity, we developed a method termed DUB-mediated identification of linkage-specific ubiquitinated substrates (DILUS) to screen the ubiquitinated lysine residues on substrates modified with certain chains and regulated by specific DUB. Then we were able to identify 166 Ubp2-regulating substrates with 244 sites potentially modified with K63-linked chains. Among these substrates, we further demonstrated that cyclophilin A (Cpr1) modified with K63-linked chain on K151 site was regulated by Ubp2 and mediated the nuclear translocation of zinc finger protein Zpr1. The K48-linked chains at non-K151 sites of Cpr1 were mainly regulated by Ubp3 and served as canonical signals for proteasome-mediated degradation.
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