Small ubiquitin-like modifier (SUMO) proteins are a family of proteins that have a similar structure with ubiquitin. There are four SUMO genes in human genome. SUMO2 and SUMO3 are highly similar (97% identical), while SUMO1 is quite distinct from other members. SUMO4 contains a specific proline90 residue, which prevents it from being processed by SUMO protease. SUMOylation is a reversible post-translational modification that covalently attaches SUMO to target proteins. SUMOylation regulates many critical cellular processes, including replication, cell-cycle, protein transport and DNA repair. SUMO is essential for almost all the eukaryotes, and deregulation of SUMOylation leads to several diseases such as cancer and neurodegenerative diseases, necessitating SUMO research. The SUMO protein capture reagent, specifically recognizes SUMO proteins and is designed for detection, characterization, and isolation of SUMOylated proteins from cells and tissue extracts.