The enzymes of the ubiquitylation pathway play a pivotal role in a number of cellular processes including the regulated and targeted proteasomal degradation of substrate proteins. Three classes of enzymes are involved in the process of ubiquitylation; activating enzymes (E1s), conjugating enzymes (E2s) and protein ligases (E3s). UBE2R2 is a member of the E2 conjugating enzyme family and cloning of the human gene was first described by Semplici et al. (2002). Site directed mutagenesis studies have shown that serine 233 in the C-terminal domain of UBE2R2 is the site at which CK2-dependent phosphorylation occurs (Semplici et al., 2002). In vitro binding experiments have also demonstrated that phosphorylated UBE2R2 and UBE2R1 bind specifically to the F-box protein beta-TRCP, which results in enhanced degradation of beta-catenin (a substrate of the Beta Transducin Repeat Containing protein (BTRC) (Semplici et al., 2002).
Semplici F, Meggio F, Pinna LA, Oliviero S (2002) CK2-dependent phosphorylation of the E2 ubiquitin conjugating enzyme UBC3B induces its interaction with beta-TrCP and enhances beta-catenin degradation. Oncogene 21, 3978-87.