6.2.1.45	ATP + ubiquitin + [E1 ubiquitin-activating enzyme]-L-cysteine = AMP + diphosphate + S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine	-	-	
6.2.1.45	ATP + ubiquitin + [E1 ubiquitin-activating enzyme]-L-cysteine = AMP + diphosphate + S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine	ATP-dependant formation of C-S thioester bond between the C-terminal glycine of ubiquitin and a sulfhydryl side group of a cysteine residue on the E1 protein	709881	
6.2.1.45	ATP + ubiquitin + [E1 ubiquitin-activating enzyme]-L-cysteine = AMP + diphosphate + S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine	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	725840	
6.2.1.45	ATP + ubiquitin + [E1 ubiquitin-activating enzyme]-L-cysteine = AMP + diphosphate + S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine	in the ATP-dependent activation reaction, ubiquitin is covalently attached to a cysteine residue of the E1 component through a thiol ester bond	725950	
6.2.1.45	ATP + ubiquitin + [E1 ubiquitin-activating enzyme]-L-cysteine = AMP + diphosphate + S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine	modeling of a cis-binding mechanism of UFM1 to UBA5, trans-binding mechanism of UFM1 transfer to the E2, UFC1, and UFM1-UBA5 adenylation domain interactions, overview. Although the active site Cys in the UBA5 apo structure is located at the N terminus of helix H, this Cys is no longer part of a helical structure in the complex with UFM1. Conformational changes in UBA5 are required to bring the active site Cys into the vicinity of UFM1-AMP mixed anhydride bond, leading to formation of the thioester bond	744655