Ub-Cys632-UBA1 adenylates ubiquitin in the cytosol

Stable Identifier
Reaction [transition]
Homo sapiens
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Activation of ubiquitin by UBA1 proceeds through 3 steps: adenylation of ubiquitin, conjugation of ubiquitin from adenyl-ubiquitin to an internal cysteine residue of UBA1, and adenylation of a second molecule of ubiquitin. In the third step, the UBA1-ubiquitin conjugate adenylates the C-terminal glycine of a second ubiquitin molecule. This results in UBA1 loaded with 2 ubiquitin molecules, one of which is conjugated to an internal cysteine residue of UBA1 and one of which is adenylated and non-covalently bound to UBA1 (Jin et al. 2007, inferred from the rabbit homologue in Haas et al. 1982, Hershko et al. 1983, reviewed in Groettrup et al. 2008).

Literature References
PubMed ID Title Journal Year
17597759 Dual E1 activation systems for ubiquitin differentially regulate E2 enzyme charging

Li, X, Gygi, SP, Jin, J, Harper, JW

Nature 2007
18353650 Activating the ubiquitin family: UBA6 challenges the field

Hofmann, K, Pelzer, C, Groettrup, M, Schmidtke, G

Trends Biochem. Sci. 2008
6277905 Ubiquitin-activating enzyme. Mechanism and role in protein-ubiquitin conjugation

Rose, IA, Hershko, A, Haas, AL, Warms, JV

J. Biol. Chem. 1982
6305978 Components of ubiquitin-protein ligase system. Resolution, affinity purification, and role in protein breakdown

Ciechanover, A, Elias, S, Heller, H, Hershko, A

J. Biol. Chem. 1983
Catalyst Activity

ubiquitin activating enzyme activity of Ub-Cys632-UBA1 [cytosol]

Orthologous Events
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