Chemical methods for protein site-specific ubiquitination.

Ubiquitination is an important protein post-translational modification regulating many cellular processes in eukaryotes. Ubiquitination is catalyzed by a three-enzyme cascade resulting in the conjugation of the C-terminal carboxylate of ubiquitin (Ub) to the ε-amino group of a lysine residue in the acceptor protein an isopeptide bond. enzymatic ubiquitination utilizing Ub ligases has been successfully employed to generate Ub dimers and polymers.