Figure 2.

Interplay of Ub and SUMO networks in DNA repair pathways. Three different scenarios underscoring the relevance of selective Ub–UBD and SUMO–SIM interactions in DNA repair pathways. (A) The SLD–SLIM-mediated deubiquitination of PCNA-Ub and FANCD2-Ub coordinates HR and TLS. (B) A ubiquitin-SUMO cross-talk mediates the assembly of DNA damage foci. (C) Polymeric chains of SUMO2/3 can trigger substrate ubiquitination by recruiting STUbLs such as RNF4 that contain repetitive SIMs. At the moment, it remains unclear whether RNF4 creates SUMO/Ub mixed chains or modifies substrates with SUMO and Ub on two separate lysine residues. See the text for more detailed descriptions.