Drosophila Chromosome 4 Chromatin Structure Figure 3. Metagene analysis shows a unique distribution of chromosomal proteins and histone marks on chromosome 4 genes. Enrichment (averaged smoothed M-values, Y-axis) for select chromosomal proteins and histone marks is plotted for a 3 kb scaled metagene (bp, X- axis). The enrichment is examined in three genomic domains: Chromosome 4 (top); pericentric heterochromatin (middle); and euchromatin (bottom) for active genes (left column) and repressed genes (right). Active genes on chromosome 4 have distinctive signatures of HP1a, POF, and H3K9me3 with highest enrichment levels across gene bodies. The number of genes included is demonstrated at the right corner for each figure. Data from BG3 cells. doi:10.1371/journal.pgen.1002954.g003 PLOS Genetics | www.plosgenetics.org 6 September 2012 | Volume 8 | Issue 9 | e1002954