Function
Ubiquitin conjugating enzyme (Ubc) or E2 enzyme catalyzes the second step in the ubiquitination of a protein tagged to be degraded by the proteasome. Ubiquitin activating enzyme (E1) and ATP produce a C-terminal acyl adenylated ubiquitin molecule which binds to ubiquitin conjugating enzyme (E2) (Ubc) cysteine[1]. The Ubc then binds to ubiquitin ligase (E3) via a conserved binding region. E3 catalyzes the transfer of ubiquitin from the Ubc-ubiquitin complex to a lysine residue of the target protein. Ubc13 makes a catalytically active heterodimer with MMS2.
For more details on Ubc13 see UBC13 MMS2.
For more details on Ubc9 see Ubc9.
Structural highlights
There are 2 distinct interactions between Ubc and ubiquitin. The first involves hydrophobic interactions between the area in Ubc around Ser22 and the ubiquitin I44. The second involves the contact between residues near the Ubc active site Cys85 and the ubiquitin TEK box[2].
