Figure 1.

Genomic Organization of Human Centromeres

(A) Human centromeres contain α-satellite sequences. In the inner core of the centromere, α-satellite monomers 171 bp long are organized into higher-order repeat (HOR) units, which are amplified, spanning 0.3–5 Mb. Unordered monomer units flank the HOR region.

(B) Functional centromeres form on a portion of the HOR, which might be newly evolved and homogenized. Disordered monomer unit sequences in pericentromeres are derived from an ancestral primate centromere. Pericentromere regions are highly heterochromatinized.