Mapping physical interactions within chromatin by proteomic approaches

Our ability to study protein–protein interactions has grown by leaps and bounds in recent years, enabling numerous large-scale studies to be performed in a variety of organisms. Despite this success, some classes of proteins, including those bound to chromatin, remain difficult to characterize through proteomic approaches. Some of the problems faced by researchers studying chromatin-bound proteins include low complex solubility, heterogeneous sample composition, and numerous transient interactions, which can be further complicated by the presence of DNA itself. To tackle these issues, a number of innovative protocols have been developed to better study the various facets of chromatin biology. In this review, we will discuss novel approaches to study protein–DNA interactions as well as protein complexes affecting chromatin.