A proposed model of role of cCTCF loci in chromatin structure. CTCF, cohesin (not shown) and possibly other factors such as Znf143 and mediator  (not shown) mediate long-range chromatin interactions through the constitutive CTCF sites. The cCTCF-mediated interactions organize/maintain the topological domains  that are units of chromosome organization. In this conceptual diagram, only constitutive CTCF sites are shown (purple ovals) and the topological domains are coloured individually.
Li et al. BMC Genomics 2013 14:553 doi:10.1186/1471-2164-14-553