NEDD8-activating enzyme E1 catalytic subunit（UBA3) is the catalytic subunit of the dimeric UBA3-NAE1 E1 enzyme， which belongs to the E1 ubiquitin-activating enzyme family. E1 activates NEDD8 by initially adenylating its C-terminal glycine residue with ATP， afterwards linking this residue to the side chain of the catalytic cysteine， generating a NEDD8-UBA3 thioester and free AMP. E1 at last transfers NEDD8 to the catalytic cysteine of UBE2M. The UBA3 enzyme connects with AppBp1， an amyloid beta precursor protein binding protein， to form a heterodimer， and at that point the enzyme complex activates NEDD8， a ubiquitin-like protein， which controls cell division， signaling and embryogenesis.
