Human Small Ubiquitin-like Modifier 2 (SUMO2), also known as Sentrin2 and SMT3B is synthesized as a 95 amino acid (aa), propeptide with a predicted 11 kDa. SUMO2 contains a two aa C-terminal prosegment and an 18 aa N-terminal protein interacting region between aa 33-50. Di-SUMO2 represents two wild-type recombinant human SUMO2 molecules linked via Lys11, which is the point of attachment for the C-terminal glycine residue of the preceding SUMO2. Human SUMO2 shares 100% aa sequence identity with mouse SUMO2. Di-SUMO2 can be used as a substrate for SUMO-specific isopeptidases (SENPs) and DeSUMOylating Isopeptidase 1 that cleave the isopeptide linkage between two SUMO2 molecules. It can also be used to investigate mechanisms of binding and recognition by SUMO-activating (E1) enzymes, SUMO-conjugating (E2) enzymes, SUMO ligases (E3s), and other proteins that contain SUMO binding domains.
SUMOs are a family of small, related proteins that can be enzymatically attached to a target protein by a post-translational modification process termed SUMOylation. Unlike SUMO1 which is usually conjugated to proteins as a monomer, SUMO2 and SUMO3 form high molecular weight polymers on proteins. All SUMO proteins share a conserved Ubiquitin domain and a C-terminal diglycine cleavage/attachment site. Following prosegment cleavage, the C-terminal glycine residue of SUMO2 is enzymatically attached to a lysine residue on a target protein. In humans, SUMO2 is conjugated to a variety of molecules in the presence of the SAE1/UBA2 SUMO-activating (E1) enzyme and the UBE2I/Ubc9 SUMO-conjugating (E2) enzyme. In yeast, the SUMO-activating (E1) enzyme is Aos1/Uba2p.