EC Number   |
Substrates  |
Products |
Reversibility |
|---|
   6.2.1.45 | more |
UBE1L2 transfers activated ubiquitin onto UbcH5b and supports E3-mediated polyubiquitylation |
? |
- |
? |
| 6.2.1.45 | more |
impaired nucleotide excision repair upon macrophage differentiation is corrected by E1 ubiquitin-activating enzyme |
? |
- |
? |
| 6.2.1.45 | more |
a lysine 48-linked polyubiquitin chain, assembled upon an internal lysine residue of a substrate protein, becomes the principle signal for recognition and target degradation by the 26S proteasome. E1 is not only essential for the initial ATP-dependent activation of ubiquitin in the ubiquitin degradtion pathway, but also capable of the catalytic extension of the polyubiquitin chain on a mono-ubiquitinated substrate |
? |
- |
? |
| 6.2.1.45 | more |
E1 consumes ATP and converts ubiquitin to a transfer-competent, enzyme-bound thioester. The reaction begins with ubiquitin-adenylate formation and the release of diphosohate. The active site cysteine of the E1 then displaces the AMP leading to a ubiquitin-E1 thioester complex |
? |
- |
? |
| 6.2.1.45 | more |
the thioester formation assay is performed using recombinant proteins expressed in Escherichia coli. The activation of ubiquitin by purified UBE1 is identified in vitro by SDS-PAGE |
? |
- |
? |
| 6.2.1.45 | more |
E1 activity is assesssed by the capacity of the enzyme to form a thiol ester conjugate with ubiquitin in an ATP-dependent process and to transfer this activated ubiquitin molecule to an conjugating enzyme |
? |
- |
? |
| 6.2.1.45 | more |
residue Cys194 lies within a region of identity to active-site Cys88 of the ubiquitin carrier protein E2, suggesting a potential role for this region in enzymatic function. Residue Cys454 lies within a region of identity to the thiol ester consensus sequence of several proteins involved in thioester formation |
? |
- |
? |
| 6.2.1.45 | more |
kinetics for Uba1a-catalyzed transthiolation of Ubc2b are used as a reporter assay for determining the Km and kcat values for the three cosubstrates of the ubiquitin-activating enzyme. The E2 transthiolation assays are more sensitive to the potential presence of trace catalytically active fragments than the single turnover end point assays used for quantitating ternary complex stoichiometry |
? |
- |
? |
| 6.2.1.45 | more |
purified isoform UBE1 can activate and conjugate ubiquitin to ubiquitin-conjugating enzyme E2s. Transfer is restricted to distinct E2 isoforms UB2R2, UBE2W and UBE2NL |
? |
- |
? |
| 6.2.1.45 | more |
chimeric mutant Aos1-Uba2 SUMO-E1 enzyme shows SUMO-E1 activity. The E1 enzyme catalyzes the formation of a thioester-linked complex between SUMO and the E2 enzyme. This process is initiated by activation of the carboxyl terminus of SUMO by adenylation, followed by a thioesterification reaction in which SUMO is conjugated to a cysteine residue at the active site of Uba2 in the E1 enzyme. SUMO is then transferred to the active site cysteine of the E2 enzyme, Ubc9, via a trans-thioesterification reaction. A SUMO-charged E2 enzyme and substrate are finally bound with or without the assistance of a distinct class of SUMO E3-ligases, resulting in the activated SUMO bound to the substrate through an isopeptide linkage |
? |
- |
? |
