Ubiquitin activating enzyme (Uba) or E1 enzyme catalyzes the first step in the ubiquitination of a protein tagged to be degraded by the proteasome. Ubiquitin activating enzyme (E1) and ATP produce a C-terminal acyl adenylated ubiquitin molecule which binds to ubiquitin conjugating enzyme (Ubc) cysteine. The Ubc then binds to ubiquitin ligase (E3) via a conserved binding region. E3 catalyzes the transfer of ubiquitin from the Ubc-ubiquitin complex to a lysine residue of the target protein. Uba3 is the catalytic subunit of NEDD8 activating enzyme and APPB1 is its regulatory subunit. Similar to ubiquitin and SUMO, NEDD8 binds to proteins after processing of its C-terminal.
3D Structures of ubiquitin activating enzyme
Updated on 25-June-2013
1z7l – mUba 1 second catalytic Cys half-domain - mouse
2v31 – mUba X first catalytic Cys half-domain
Uba1
3cmm – yUba + ubiquitin – yeast
4ii2 – hUba + E2 Ubc4 + ubiquitin-ribosomal protein L40 + ATP
4ii3 – hUba + ubiquitin-ribosomal protein L40 + ATP
Uba2
3ong, 3onh – yUba + SUMO-conjugating enzyme Ubc9
NEDD8-activating enzyme Uba3 subunit
2lq7 – hUba – human
1r4m – hUba + NEDD8
1r4n – hUba (mutant) + NEDD8 + APPBP1 + ATP
1tt5 – hUba + E2 Ubc12 + APPBP1
1y8x – hUba + E2 Ubc12
1yov – hUba + APPBP1
3dbr – hUba + APPBP1 (mutant) + NEDD8
2nvu – hUba + E2 Ubc12 + APPBP1 + NEDD8 + ATP
3gzn – hUba + inhibitor + APPBP1 + NEDD8 + ATP
3dbh, 3dbl – hUba (mutant) + NEDD8
3fn1 – hUba (mutant) + NEDD8-conjugating enzyme
Uba5
3guc – hUba + AMPPNP
3h8v – hUba + ATP
SUMO-activating enzyme
3kyc – hSua subunits 1,2 + SUMO
3kyd – hSua subunits 1,2 + SUMO + AMP
