The heterodimer acts as a E1 ligase for SUMO1, SUMO2, SUMO3, and probably SUMO4. It mediates ATP-dependent activation of SUMO proteins followed by formation of a thioester bond between a SUMO protein and a conserved active site cysteine residue on UBA2/SAE2.
Expression level increases during S phase and drops in G2 phase (at protein level).
Protein modification; protein sumoylation.
Belongs to the ubiquitin-activating E1 family.
Phosphorylated upon DNA damage, probably by ATM or ATR.