Byrum, S.D. et al. Cell Reports 2, 198–205 (2012).

It's not just DNA that matters—it's what binds to it that exerts regulatory influence. Chromatin modification is an intricately orchestrated process that involves many players such as remodeling proteins and histones. Capturing this assembly in an unbiased fashion at a specific genomic locus is far from a trivial task because current methods such as chromatin immunoprecipitation only look at one player at a time. To achieve simultaneous profiling of multiple targets, Byrum et al. have developed chromatin affinity purification coupled with mass spectrometry (ChAP-MS). They isolated a 1,000-kb region around a transcriptionally active or inactive GAL1 promoter in yeast and compared the associated proteins and histone modifications. This molecular snapshot at a specific locus will allow insights into epigenetic regulatory mechanisms.