SUMO monoclonal antibodies vary in sensitivity, specificity, and ability to detect SUMO conjugate types.

Monoclonal antibodies (MAb) to members of the Small Ubiquitin-like modifier (SUMO) family are essential tools in the study of cellular SUMOylation. However, many reagents are poorly validated, and the choice of which antibody to use for which detection format is without an evidence base. Here we test twenty-four anti-SUMO monoclonal antibodies for sensitivity and specificity to SUMO1-4 in monomeric and polymeric states in dot-blots, immunoblots, immunofluorescence and immunoprecipitation. We find substantial variability between SUMO MAbs for different conjugation states, detection of increased SUMOylation in response to thirteen different stress agents and as enrichment reagents for analysis of SUMOylated RanGAP1 or KAP1. All four anti-SUMO4 monoclonal antibodies tested cross-reacted with SUMO2/3, and several SUMO2/3 monoclonal antibodies cross-reacted with SUMO4. ~10% of tested monoclonal antibodies produced specific results across multiple applications.