Fig. 7: Model for the geometry of human centromere components.
From: Defining a core configuration for human centromeres during mitosis
Centromeric DNA on mitotic human chromosomes is organized in 3D, with pericentromeric cohesive domains and a kinetochore-assembly domain composed of α-satellite DNA. We speculate α-satellite DNA from each sister forms a primary extensible loop with CENP-A enriched chromatin at its tip. This loop may form as a consequence of loop extrusion by cohesin at its base. The primary α-satellite loop may contain several minor loops which can be small or large (dotted lines) depending on the size of the α-satellite HOR array in a bottlebrush configuration. These may be maintained by additional structural proteins, such as condensins. The extensible loop must be able to withstand microtubule forces and thus is potentially tethered to the pericentromeric DNA by cohesin or other structural proteins. The CENP-A associated tip of the α-satellite DNA may be further organized by cohesin, observed variably by imaging and not by ChIP.
