FIG. 4.

CTCF is required for allele-specific chromatin composition locally and at a distance. Quantitative analyses of chromatin composition reveal the consequences of ICR CTCF site mutations. Allele-specific enrichment is no longer apparent: the activating globular domain histone marks H4K91ac (A), H3K79me1 (B), and H3K79me2 (C) have shifted toward the maternal allele at the Igf2 locus. (D) H3K79me3 has shifted toward the maternal allele at the H19 locus. Chromatin was precipitated from CTCFm × CS MEFs in duplicate with the specific antibodies indicated on top of each chart. Allele-specific histone modification at a specific region was expressed as a percentage of the maternal mutant (MATmut) or paternal wild type (PAT) allele in the total immunoprecipitate.