IUBMB Enzyme Nomenclature


Accepted name: E2 ubiquitin-conjugating enzyme

Reaction: S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine + [E2 ubiquitin-conjugating enzyme]-L-cysteine = [E1 ubiquitin-activating enzyme]-L-cysteine + S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine

Other name(s): ubiquitin-carrier-protein E2; UBC (ambiguous); ubiquitin-conjugating enzyme E2

Systematic name: S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine:[E2 ubiquitin-conjugating enzyme] ubiquitinyl transferase

Comments: The E2 ubiquitin-conjugating enzyme acquires the activated ubquitin from the E1 ubiquitin-activating enzyme (EC and binds it via a transthioesterification reaction to itself. In the human enzyme the catalytic center is located at Cys-87 where ubiquitin is bound via its C-terminal glycine in a thioester linkage.

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


1. van Wijk, S.J. and Timmers, H.T. The family of ubiquitin-conjugating enzymes (E2s): deciding between life and death of proteins. FASEB J. 24 (2010) 981-993. [PMID: 19940261]

2. David, Y., Ziv, T., Admon, A. and Navon, A. The E2 ubiquitin-conjugating enzymes direct polyubiquitination to preferred lysines. J. Biol. Chem. 285 (2010) 8595-8604. [PMID: 20061386]

3. Papaleo, E., Casiraghi, N., Arrigoni, A., Vanoni, M., Coccetti, P. and De Gioia, L. Loop 7 of E2 enzymes: an ancestral conserved functional motif involved in the E2-mediated steps of the ubiquitination cascade. PLoS One 7 (2012) e40786. [PMID: 22815819]

4. Cook, B.W. and Shaw, G.S. Architecture of the catalytic HPN motif is conserved in all E2 conjugating enzymes. Biochem. J. 445 (2012) 167-174. [PMID: 22563859]

5. Li, D.F., Feng, L., Hou, Y.J. and Liu, W. The expression, purification and crystallization of a ubiquitin-conjugating enzyme E2 from Agrocybe aegerita underscore the impact of His-tag location on recombinant protein properties. Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 69 (2013) 153-157. [PMID: 23385757]

[EC created 2015]

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