SUMO Activating Enzyme Subunit 1 (SAE1)

Posttranslational modification of proteins by the addition of the small protein SUMO, or sumoylation, regulates protein structure and intracellular localization. SAE1 and UBA2 form a heterodimer that functions as a SUMO-activating enzyme for the sumoylation of proteins.The deduced SAE1 and SAE2 proteins contain 347 and 640 amino acids, respectively.SAE1 shares sequence similarity with the N terminus of ubiquitin-activating E1 enzymes, and SAE2 share sequence similarity with the C terminus of E1 enzymes. Both SAE subunits contain a conserved nucleotide-binding motif, and SAE2 contains an E1-like active-site cysteine. SAE1 has a calculated molecular mass of 38 kD. It had an apparent molecular mass of 40 kD by SDS-PAGE.