Absolute quantification of proteins and histone modifications in Drosophila embryos reveals stoichiometric relationships in chromatin regulation. Absolute quantification of proteins and histone modifications in Drosophila embryos reveals stoichiometric relationships in chromatin regulation

High-level H3K27me3 domains are required for proper gene repression mediated by Polycomb proteins. Genome-wide profiling of H3K27 methylation during developmental progression and in animals with reduced PRC2 levels illustrates how mass spectrometry-based normalization permits the quantitative analysis of changes in chromatin states. Overall design: Definition of high-level H3K27me3 domains by genome segmentation, direct comparison of H3K27me3 profiles in 2-4 hr and 14-16 hr wt embryos as well as in 0-6 hr wt and esc mutant embryos.