Figure 1. Overview of human X centromere region.

A. The short (Xp) and long (Xq) arm sides of the centromere are designated. The solid black bar represents higher order repeat (HOR) DXZ1 alpha satellite DNA which is composed of highly ordered 171 bp monomers organized into multi-megabased arrays. The array is not drawn to scale and is shown as the point from which the other pericentromeric genomic positions are centered. Each type of pericentromeric DNA is designated by differently shaded boxes. Regions of unordered alpha satellite monomers flank HOR alpha satellite. The short arm pericentromere contains other types of satellites such as gamma satellite and HSAT4. The junctions between DXZ1 alpha satellite (array junction) and between monomeric satellite and the chromosome arms (satellite junction) are denoted by arrowheads. The two sites located 150 kb outside of the centromere, ZXDA and LTR/LINE, are depicted because they were included in the ChIP analyses. The location of chromatin domains for CENP-A chromatin (kinetochore) and the flanking pericentromere (heterochromatin) are shown relative to the schematic genomic region. B. ChIP analysis using antibodies specific for mouse Cenp-A were used to confirm that mouse Cenp-A replaces human CENP-A at higher order alpha satellite DNA on the X chromosome that was transferred into a mouse cell line. ZXDA was used for normalization and establishment of background levels of enrichment (n = 3 with SD). Asterisks indicate statistically significant differences as calculated by a Student's t-test (p<0.05).