Small ubiquitin-like modifier (SUMO) is a small molecule, but has a variety of regulatory functions in cells [1-3]. SUMO modification is involved in transcriptional regulation, subcellular localization, and protein-protein interactions. SUMO conjugation requires sequential E1-dependent activation, E2-dependent conjugation, and E3-dependent ligation steps. Similar to protein phosphorylation, ubiquitination, acetylation, and methylation, SUMO conjugation and deconjugation are a dynamic processes. SUMOylating enzymes add SUMO to protein substrates, whereas deSUMOylating enzymes remove SUMO from SUMO-conjugated proteins. Many transcription factors and coregulators are SUMOylated and SUMOylation of these factors are mainly involved in transcriptiona repression mechanism [4, 5].
SUMOylation and deSUMOylation assays are available to investigate the dynamics of SUMOylation/deSUMOylation process, and provide exciting ways to study transcriptional regulatory mechanisms. This protocol details both in vivo and in vitro SUMOylation/deSUMOylationg assays that provide combined molecular approaches to study cellular functions of chromatin remodelling complexes.