SUMO E1

SUMO (Small Ubiquitin-related Modifier) is a ubiquitin-like family member that regulates a wide range of key cellular events. Sumoylation of proteins alters their intracellular localization, stability, and interaction with other proteins. SUMO is conjugated to its substrates utilizing a cascade of events involving activation with E1 enzyme (SAE1/SAE2), conjugation involving the E2 enzyme (UBC9), and substrate modification through the cooperation of the E2 and E3 protein ligases. SUMO and Nedd8 pathways utilize a single E1 and a single E2 in combination with a few known E3s. The dimeric activating enzyme E1 utilizes ATP to adenylate the C-terminal glycine residue of all SUMO proteins, forming a high- energy thiolester bond with the cysteine residue of SAE2. SUMO E1 enzyme is a heterodimer of His-tagged SAE1 and un-tagged SAE2.