complex(a(MESH:Ubiquitin), p(HGNC:UBA3))

Components

• a(MESH:Ubiquitin)
• p(HGNC:UBA3)

One of several E2 enzymes (ubiquitin-carrier proteins or Ubiquitin-Conjugating enzymes [UBCs]) transfers the activated ubiquitin moiety from E1, via an additional high-energy thiol ester intermediate, E2-S~ubiquitin, to the substrate that is specifically bound to an E3, a member of the ubiquitinprotein ligase family of proteins PubMed:14556719

Both HECT and RBR E3s are unique in comparison to the RING ligases because they catalyze an additional transthioesterification step, where ubiquitin is transferred from the E2 to the E3 before its conjugation to the protein substrate (Figure 1A) PubMed:24457024

Both HECT and RBR E3s are unique in comparison to the RING ligases because they catalyze an additional transthioesterification step, where ubiquitin is transferred from the E2 to the E3 before its conjugation to the protein substrate (Figure 1A) PubMed:24457024

In summary, mechanisms of E2 activation involve the binding of ubiquitin to surfaces on the E2 and/or E3, thereby allowing an optimal conformation of ubiquitin on the E2 surface PubMed:24457024