CpG sequences at the promoter and CTCF-binding regions of DXZ4 are methylated on the active X but unmethylated on the inactive X chromosome. Gray arrows at the top of the image represent a single DXZ4 monomer, with the region under analysis highlighted (498–1033 bp). Below shows the CpG methylation status of the region for two independent male and four independent female cell lines. The location of the minimal promoter region and the smallest CTCF EMSA fragment are indicated by the black boxes and the gray shadow. Each line represents the sequence of an individual clone. The location of CpG sequences is indicated by the circles on the lines, with open circles indicating unmethylated and black filled circles as methylated CpGs.
