E3 ligase Rad18 promotes monoubiquitination rather than ubiquitin chain formation by E2 enzyme Rad6.

@article{Hibbert2011E3LR,
  title={E3 ligase Rad18 promotes monoubiquitination rather than ubiquitin chain formation by E2 enzyme Rad6.},
  author={Richard Hibbert and Anding Huang and Rolf Boelens and Titia Sixma},
  journal={Proceedings of the National Academy of Sciences of the United States of America},
  year={2011},
  volume={108 14},
  pages={5590-5}
}
In ubiquitin conjugation, different combinations of E2 and E3 enzymes catalyse either monoubiquitination or ubiquitin chain formation. The E2/E3 complex Rad6/Rad18 exclusively monoubiquitinates the proliferating cell nuclear antigen (PCNA) to signal for "error prone" DNA damage tolerance, whereas a different set of conjugation enzymes is required for ubiquitin chain formation on PCNA. Here we show that human E2 enzyme Rad6b is intrinsically capable of catalyzing ubiquitin chain formation. This… CONTINUE READING