Site-specific characterization of Asp- and Glu-ADP-Ribosylation by quantitative mass spectrometry

Adenosine diphosphate (ADP)-ribosylation is a protein posttranslational modification where either mono ADP-ribose or poly ADP-ribose units are attached an acceptor protein. ADP-ribosylation is catalyzed by a class of enzymes known as poly(ADP-ribose) polymerases (PARPs). A large number of nuclear proteins have been described to be ADP-ribosylated, including PARP1 and many other components of the DNA damage repair machinery. During the past decade, intensive research has been focused on understanding the upstream signaling of PARPs. In contrast, the downstream targets of PARPs and their specific sites of ADP-ribosylation remain poorly characterized. Mass-spectrometry-based proteomics approaches are powerful tools to study protein posttranslational modifications. In the last couple of years, we have developed an integrative proteomic platform, and we used this approach for the quantitative characterization of protein ADP-ribosylation on a global scale. We expect that the data sets generated from these studies will serve as an invaluable resource, providing the foundation for future hypothesis-driven research that helps delineate the molecular mechanisms that underlie protein ADP-ribosylation and its regulated pathophysiological processes.