Reaction catalyzed by E2 ubiquitin-conjugating enzyme (2.3.2.23)

	[ubiquitin-activating protein UBE1]-S-ubiquitinyl-L-cysteine	+		[ubiquitin carrier protein UBE2W]-L-cysteine	=		[ubiquitin-activating protein UBE1]-L-cysteine	+		[ubiquitin carrier protein UBE2W]-S-ubiquitinyl-L-cysteine
	[ubiquitin-activating protein UBE1]-S-ubiquitinyl-L-cysteine	+		[ubiquitin carrier protein UBE2W]-L-cysteine	=		[ubiquitin-activating protein UBE1]-L-cysteine	+		[ubiquitin carrier protein UBE2W]-S-ubiquitinyl-L-cysteine