Terminal erythroid maturation is associated with loss of histone PTM associated with active transcriptional elongation. (A) Schematic demonstrating CD36 erythroid synchronization culture system. CD34-positive cells are expanded for 7 days before CD36 selection. CD36-positive cells are cultured for an additional 11 days allowing for terminal erythroid maturation. (B) Cytospins of cells at day 7 and day 10 of terminal erythroid maturation. (C) Heat map of changes in histone abundance during terminal erythroid maturation as determined by mass spectrometry. Values represent log₂ fold change of day 10 compared with day 7 of terminal erythroid maturation. (D) Abundance of histone modifications associated with active transcription by RNA polymerase II on day 7 and day 10 of terminal maturation. (E) Fold change of transcription related histone marks at day 10 relative to day 7. (F) Abundance of histone methylation PTM at day 7 and day 10 of terminal maturation. Only histone PTM present at greater than 1% abundance are shown. (G) Fold change of histone methylation at day 10 relative to day 7. (H) Abundance of histone PTMs associated with heterochromatin at day 7 and day 10 of terminal maturation. Only histone PTMs with an abundance greater than 1% are shown. (I) Fold change of heterochromatin-associated PTMs at day 10 relative to day 7. (J) Abundance of histone acetylation at day 7 and day 10 of terminal maturation. Only histone PTMs with an abundance greater than 1% are shown. (K) Fold change of histone acetylation marks at day 10 relative to day 7. The data in this figure represent 2 biologic and 6 technical replicates. Error bars represent standard error of the mean.