Isolation of Chromatin Proteins by Genome Capture

Control of gene expression and the faithful transmission of genetic and epigenetic information rely on chromatin-bound proteins. These include the polycomb group of proteins, which can display a remarkable variability in their composition. Alterations in the chromatin-bound protein compositions are relevant for physiology and human disease. Thus, chromatin-bound proteomic profiling can be instrumental for understanding fundamental cellular processes and for identifying therapeutic targets. Inspired by biochemical strategies for the isolation of proteins on nascent DNA (iPOND) and the very similar DNA-mediated chromatin pull-down (Dm-ChP), we described a method for the identification of Protein on Total DNA (iPOTD) for bulk chromatome profiling. Here, we update our iPOTD method and, in particular, detail the experimental procedure for the isolation of chromatin proteins for mass spectrometry-based proteomic analysis.