The ubiquitin E1 activating enzyme UbE1 is responsible for the first step in ubiquitin conjugation cascade and acts by first adenylating with ATP the C-terminal glycine carboxyl group of ubiquitin followed by transfer to the sulphydryl side chain moiety of a UbE1 cysteine active site residue, to give a high energy thioester bond and liberating free AMP. There are two active sites within the E1 molecule allowing it to accommodate two ubiquitin molecules at one time, with a new ubiquitin forming an adenylate intermediate as the previous one is transferred to the thiol site. The activated ubiquitin is then transferred to the lysine of target proteins via the E2 / E3 conjugation cascade.
Recombinant human UbE1 protein expressed with a C-terminal His-tag. Essential enzyme for use in ubiquitin chain synthesis and protein ubiquitination reactions.
