Human CTCF Interacts with Drosophila CP190, but not with Kaiso.

Human CTCF (hCTCF) is a major architectural protein in mammals. In Drosophila, the CTCF homologue (dCTCF) interacts with the BTB domain of the CP190 protein, which is involved in the establishment of open chromatin and activity of insulators. Previously, it was shown that the BTB protein Kaiso interacts with hCTCF and regulates its activity. We have carried out a detailed study of the interaction between these proteins in the yeast two-hybrid assay. Surprisingly, Kaiso did not interact with hCTCF and its Drosophila homologue. On the other hand, CP190 interacted with the C-terminus of hCTCF. The results obtained demonstrate that the interaction between CTCF and CP190 proteins is highly conserved. It is likely that humans have other BTB proteins that perform the functions described for the Drosophila CP190.