IUBMB Enzyme Nomenclature


Accepted name: E1 ubiquitin-activating enzyme

Reaction: ATP + ubiquitin + [E1 ubiquitin-activating enzyme]-L-cysteine = AMP + diphosphate + S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine

Other name(s): ubiquitin activating enzyme; E1; ubiquitin-activating enzyme E1

Systematic name: ubiquitin:[E1 ubiquitin-activating enzyme] ligase (AMP-forming)

Comments: Catalyses the ATP-dependent activation of ubiquitin through the formation of a thioester bond between the C-terminal glycine of ubiquitin and the sulfhydryl side group of a cysteine residue in the E1 protein. The two-step reaction consists of the ATP-dependent formation of an E1-ubiquitin adenylate intermediate in which the C-terminal glycine of ubiquitin is bound to AMP via an acyl-phosphate linkage, then followed by the conversion to an E1-ubiquitin thioester bond via the cysteine residue on E1 in the second step.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Haas, A.L., Warms, J.V., 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]

2. Huzil, J.T., Pannu, R., Ptak, C., Garen, G. and Ellison, M.J. Direct catalysis of lysine 48-linked polyubiquitin chains by the ubiquitin-activating enzyme. J. Biol. Chem. 282 (2007) 37454-37460. [PMID: 17951259]

3. Zheng, M., Liu, J., Yang, Z., Gu, X., Li, F., Lou, T., Ji, C. and Mao, Y. Expression, purification and characterization of human ubiquitin-activating enzyme, UBE1. Mol. Biol. Rep. 37 (2010) 1413-1419. [PMID: 19343538]

4. Carvalho, A.F., Pinto, M.P., Grou, C.P., Vitorino, R., Domingues, P., Yamao, F., Sa-Miranda, C. and Azevedo, J.E. High-yield expression in Escherichia coli and purification of mouse ubiquitin-activating enzyme E1. Mol Biotechnol 51 (2012) 254-261. [PMID: 22012022]

[EC created 2015]

Return to EC 6.2.1 home page
Return to EC 6.2 home page
Return to EC 6 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page