The scheme of SUMOylation and deSUMOylation pathway. (A) Protein SUMOylation is associated with a recycling system consisting of conjugation and deconjugation pathways. Both conjugation and deconjugation enzymes mediate the dynamic and reversible process of SUMOylation. The protein SUMOylation alters protein activation, transcriptional activity, stability, and localization change. (B) SUMO proteins covalently modify certain residues of specific target substrates and change the function of these substrates. The conjugation pathway is mediated by SUMO E1, E2, E3 enzymes, whereas the deconjugation pathway is mediated by SUMOisopeptidase, SENPs.