IUBMB Enzyme Nomenclature


Accepted name: ubiquitin—protein ligase

Reaction: ATP + ubiquitin + protein lysine = AMP + diphosphate + protein N-ubiquityllysine

Other name(s): ubiquitin-activating enzyme

Systematic name: ubiquitin:protein-lysine N-ligase (AMP-forming)

Comments: Ubiquitin is coupled to protein by a peptide bond between the C-terminal glycine of ubiquitin and ε-amino groups of lysine residues in the protein. An intermediate in the reaction contains one ubiquitin residue bound as a thioester to the enzyme, and a residue of ubiquitin adenylate non-covalently bound to the enzyme.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 74812-49-0


1. Ciechanover, A., Elias, S., Heller, H. and Hershko, A. "Covalent affinity" purification of ubiquitin-activating enzyme. J. Biol. Chem. 257 (1982) 2537-2542. [PMID: 6277904]

2. Haas, A.L. and Rose, I.A. The mechanism of ubiquitin activating enzyme. A kinetic and equilibrium analysis. J. Biol. Chem. 257 (1982) 10329-10337. [PMID: 6286650]

3. Haas, A.L., Warms, J.V.B., Hershko, A. and Rose, I.A. Ubiquitin-activating enzyme. Mechanism and role in protein-ubiquitin conjugation. J. Biol. Chem. 257 (1982) 2543-2548. [PMID: 6277905]

4. Hershko, A., Heller, H., Eytan, E. and Reiss, Y. The protein substrate binding site of the ubiquitin-protein ligase system. J. Biol. Chem. 261 (1986) 11992-11999. [PMID: 3017957]

[EC created 1986]

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