Reaction catalyzed by (E3-independent) E2 ubiquitin-conjugating enzyme (2.3.2.24)

	S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine	+		Ube2g2-L-cysteine	=		[E1 ubiquitin-activating enzyme]-L-cysteine	+		S-monoubiquitinyl-Ube2g2-L-cysteine
	S-ubiquitinyl-[E1 ubiquitin-activating enzyme]-L-cysteine	+		Ube2g2-L-cysteine	=		[E1 ubiquitin-activating enzyme]-L-cysteine	+		S-monoubiquitinyl-Ube2g2-L-cysteine