Project 1: Identification of SUMOylated proteins which are regulated by the SUMO protease SENP6. SENP6 knockdown was performed by two independent shRNAs and SUMOylated proteins were purified from U2OS expressing His10-tagged SUMO2 by means of Ni-NTA pulldown. Purified SUMOylated proteins were identified and quantified by label-free quantification. Project 2: Dynamics of chromatin-associated proteins influenced by SENP6. After siRNA-mediated knockdown of SENP6, chromatin fractions of U2OS cells were isolated and abundances of proteins were quantified. Project 3: Analysis of in vitro SUMOylated CENP-T for the presence of SUMOylated SUMO peptides. For this aim purified CENP-T-HA was in vitro SUMOylated with a SUMO Q87R mutant to reduce the length of the tryptic peptide and therefore to be able to identified sit-specific SUMOylation.