Ubiquitin Activating Enzyme (E1, E1/UBAE, ubiquitin-activating. Human specificity) ELISA Kit

4°C

Ubiquitin-activating enzyme, (or E1), is involved in the first step of ubiquitination. At the start of the ubiquitination cascade, the E1 enzyme binds ATP-Mg2+ and ubiquitin and catalyses ubiquitin C-terminal acyl adenylation. In the next step a catalytic cysteine on the E1 enzyme attacks the ubiquitin-AMP complex through acyl substitution, simultaneously creating a thioester bond and an AMP leaving group. Finally, the E1ca.ubiquitin complex transfers ubiquitin to an E2 enzyme through a transthioesterification reaction, in which an E2 catalytic cysteine attacks the backside of the E1ca.ubiquitin complex. Throughout this mechanism, the E1 enzyme is bound to two ubiquitin molecules. Although this secondary ubiquitin is similarly adenylated, it does not form the same thioester complex described previously. The function of the secondary ubiquitin remains largely unknown, however it is believed that it may facilitate conformational changes seen in the E1 enzyme during the transthioesterification process.