SUMO-activating enzyme subunit 2 (UBA2)

The heterodimer acts as an 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.

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