Figure 2. Sequence, structure, and epigenetic map of the chromosome 8 centromeric region.

a) Schematic showing the composition of the CHM13 chromosome 8 centromere. The centromeric region is comprised of a 2.08 Mbp D8Z2 α-satellite HOR array flanked by regions of monomeric and/or divergent α-satellite interspersed with retrotransposons, β-satellite, and ɣ-satellite. The predicted restriction digest pattern is shown. The D8Z2 α-satellite HOR array is heavily methylated except for a 73 kbp hypomethylated region, which is encompassed by a 632 kbp CENP-A chromatin domain (Extended Data Fig. 9, Supplementary Fig. 8). A pairwise sequence identity heatmap indicates that the centromere is composed of five distinct evolutionary layers (dashed arrows). b) PFG Southern blot of CHM13 DNA confirms the structure and organization of the chromosome 8 centromeric HOR array. Left: EtBr staining; Right: P³²-labeled chromosome 8 α-satellite-specific probe; n = 2. For gel source data, see Supplementary Fig. 9a,b. c) Representative images of a CHM13 chromatin fiber showing CENP-A enrichment in an unmethylated region. n = 3; bar = 1 micron.