Fig. 1.

DUB esterases as part of the ubiquitin code arsenal. Protein substrate (de)-ubiquitylation on different amino acid side chains. (A) Classical ubiquitin (Ub) conjugation and deubiquitylation of lysine “isopeptide bonds.” (B) Cys-ubiquitylation yielding Ub-thioesters, mostly prevalent in transthioylation reactions involving E1, E2, and E3 enzymes. (C) Ser/Thr ubiquitylation and cleavage via DUBs (in red) from the USP, UCH, MJD, and OTU subfamilies. Scissors indicate DUB esterase activities (in red).