UBC13 MMS2: Difference between revisions

<Structure load='1J7D' size='350' frame='true' align='right' caption='UBC13 with MMS2. UBC13 is shown in green and MMS2 is shown in blue Structure determined by Moraes, T.F.,  Edwards, R.A.,  McKenna, S.,  Pastushok, L.,  Xiao, W.,  Glover, J.N.,  Ellison, M.J.' scene='Insert optional scene name here' />

UBC13 is an E2 ubiquitin conjugating enzyme that can form a heterodimer with Mms2 to function as a part of the Translesion DNA Synthesis Pathway (TLS). When bound to Mms2, Ubc13 will polyubiquinate PCNA, Proliferating Cell Nuclear Antigen, a sliding clamp protein at the DNA transcription fork. UBC13-MMS2 functions to polyubiquinate PCNA following the initial monoubiquitination by Rad6-Rad18(another E2 complex).

UBC13 functions as a heterodimer with MMS2, a structurally similar protein to UBC13, but lacking the catalytic Cysteine residue in the active site.  The UBC13 E2 complex with MMS2 functions primarily to enhance DNA repair from double stranded breaks.  MMS2 bound to UBC13 helps orient the Ubiquitin molecule for proper Ubiquitination of the K63 residue.  MMS2 is considered a UEV protein (Ubiquitin-conjugating Enzyme Variant), because it lacks the catalytic Cysteine residue necessary for proper thioester formation.