Of proteins and DNA--proteomic role in the field of chromatin research.

To paraphrase Robert Burns's poem To a Mouse, the best laid schemes of DNA-protein complex purification often go awry. Chromatin with its heterogeneous and dynamic protein composition remains difficult to analyze. Still critical progress has been made in recent years in characterizing the interface between DNA and proteins due, in part, to significant advances in proteomic technologies. Proteomics has progressed to a point where affinity purification of soluble complexes and protein identification by mass spectrometry are routine. The new challenge for chromatin proteomics lies in studying proteins and protein complexes in their native environment, which is on chromatin. These novel types of data represent an additional layer of information that can be used to better characterize and understand cellular processes. This review will focus on the past contributions as well as on emerging mass spectrometry-based methodologies attempting to better define the complex relationship between proteins, protein complexes and DNA.