2.3.2.23	[ubiquitin-activating protein Uba1a]-S-ubiquitinyl-L-cysteine + [ubiquitin-carrier-protein Ubc2b]-L-cysteine	-	[ubiquitin-activating protein Uba1a]-L-cysteine + [ubiquitin-carrier-protein Ubc2b]-S-ubiquitinyl-L-cysteine	-	?	429048	
2.3.2.23	[ubiquitin-activating protein UBA1]-S-ubiquitinyl-L-cysteine + [ubiquitin carrier protein E2]-L-cysteine	transfer of ubiquitin from activating protein UBA1 can take place to different ubiquitin-carrier enzymes E2, with little discrimination for the type of E2 protein	[ubiquitin-activating protein BA1]-L-cysteine + [ubiquitin carrier protein E2]-S-ubiquitinyl-L-cysteine	-	?	429049	
2.3.2.23	[ubiquitin-activating protein Uba1]-S-ubiquitinyl-L-cysteine + [ubiquitin-carrier-protein Ubc2b]-L-cysteine	-	[ubiquitin-activating protein Uba1]-L-cysteine + [ubiquitin-carrier-protein Ubc2b]-S-ubiquitinyl-L-cysteine	-	?	429050	
2.3.2.23	[ubiquitin-activating protein UBA2]-S-ubiquitinyl-L-cysteine + [ubiquitin carrier protein E2]-L-cysteine	transfer of activated ubiquitin from E1 enzyme UBA2 is carried out to different ubiquitin-carrier enzymes E2, with little discrimination for the type of E2 protein	[ubiquitin-activating protein UBA2]-L-cysteine + [ubiquitin carrier protein E2]-S-ubiquitinyl-L-cysteine	-	?	429051	
2.3.2.23	[ubiquitin-activating protein Uba3]-S-ubiquitinyl-L-cysteine + [ubiquitin-carrier-protein Ubc12]-L-cysteine	-	[ubiquitin-activating protein Uba3]-L-cysteine + [ubiquitin-carrier-protein Ubc12]-S-ubiquitinyl-L-cysteine	-	?	429052	
2.3.2.23	[ubiquitin-activating protein Uba6]-S-ubiquitinyl-L-cysteine + [ubiquitin carrier protein UbcH5B]-L-cysteine	-	[ubiquitin-activating protein Uba]-L-cysteine + [ubiquitin carrier protein UbcH5B]-S-ubiquitinyl-L-cysteine	recombinant E1 enzyme Uba6 can activate ubiquitin and transfer it onto the ubiquitin-conjugating enzyme UbcH5B. Ubiquitin activated by Uba6 can be used for ubiquitylation of p53 and supports the autoubiquitylation of the E3 ubiquitin ligases HectH9 and E6-AP	?	429053	
2.3.2.23	[ubiquitin-activating protein UBE1]-S-ubiquitinyl-L-cysteine + [ubiquitin carrier protein E2]-L-cysteine	purified E1 enzyme UBE1 can activate and conjugate ubiquitin to ubiquitin-conjugating enzyme E2s. Transfer is restricted to distinct E2 isoforms UB2R2, UBE2W and UBE2NL	[ubiquitin-activating protein UBE1]-L-cysteine + [ubiquitin carrier protein E2]-S-ubiquitinyl-L-cysteine	-	?	429054	
2.3.2.23	[ubiquitin-activating protein UBE1]-S-ubiquitinyl-L-cysteine + [ubiquitin carrier protein UB2R2]-L-cysteine	purified E1 enzyme UBE1 can activate and conjugate ubiquitin to ubiquitin-conjugating enzyme E2s. Transfer is restricted to distinct E2 isoforms UB2R2, UBE2W and UBE2NL	[ubiquitin-activating protein UBE1]-L-cysteine + [ubiquitin carrier protein UB2R2]-S-ubiquitinyl-L-cysteine	-	?	429055	
2.3.2.23	[ubiquitin-activating protein UBE1]-S-ubiquitinyl-L-cysteine + [ubiquitin carrier protein UBE2NL]-L-cysteine	purified E1 enzyme UBE1 can activate and conjugate ubiquitin to ubiquitin-conjugating enzyme E2s. Transfer is restricted to distinct E2 isoforms UB2R2, UBE2W and UBE2NL	[ubiquitin-activating protein UBE1]-L-cysteine + [ubiquitin carrier protein UBE2NL]-S-ubiquitinyl-L-cysteine	-	?	429056	
2.3.2.23	[ubiquitin-activating protein UBE1]-S-ubiquitinyl-L-cysteine + [ubiquitin carrier protein UBE2W]-L-cysteine	purified E1 enzyme UBE1 can activate and conjugate ubiquitin to ubiquitin-conjugating enzyme E2s. Transfer is restricted to distinct E2 isoforms UB2R2, UBE2W and UBE2NL	[ubiquitin-activating protein UBE1]-L-cysteine + [ubiquitin carrier protein UBE2W]-S-ubiquitinyl-L-cysteine	-	?	429057