6K2U:
reference: Threonine ADP-Ribosylation of Ubiquitin by a Bacterial Effector Family Blocks Host Ubiquitination., Yan F, Huang C, Wang X, Tan J, Cheng S, Wan M, Wang Z, Wang S, Luo S, Li A, Guo X, Feng M, Liu X, Zhu Y, Zhou Y, Mol Cell. 2020 May 21;78(4):641-652.e9. doi: 10.1016/j.molcel.2020.03.016. Epub, 2020 Apr 23. PMID: 32330457

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