Protein ubiquitination is an important post-translational modification (PTM) that regulates almost every aspect of cellular function and many cell signalling pathways in eukaryotes. Alterations of protein ubiquitination have been linked to many diseases, such as cancer, neurodegenerative diseases, cardiovascular diseases, immunological disorders, and inflammatory diseases. In order to understand the roles of protein ubiquitination in these diseases and in cell signalling pathways, it is necessary to identify ubiquitinated proteins and their modification sites.
The use of mass spectrometry to identify sites of ubiquitination within target proteins in vivo will allow greater understanding of the ways in which ubiquitination alters protein function. Therefore, the development of broadly applicable identification approaches is critical. Ubiquitination sites can be identified by MS through the detection of peptide adducts derived from ubiquitin.