Ibf1 and Ibf2 are DNA-binding proteins required for insulator function in Drosophila [ChIP-seq]

Here we report on the identification of two previously uncharacterized proteins as CP190 interacting proteins, that we have named Ibf1 and Ibf2. These proteins localize at insulator bodies and associate with chromatin at CP190-binding sites throughout the genome. We also show that Ibf1 and Ibf2 are DNAbinding proteins that form obligated hetero-oligomers that mediate CP190 binding to chromatin. Moreover, Ibf1 and Ibf2 are necessary for insulator activity in enhancerblocking assays. Taken together our data reveal a novel pathway of CP190 recruitment to chromatin that is required for insulator activity. Overall design: ChIP-Seq peak calling of CP190, Ibf1 and Ibf2 against Input sample in Drosophila melanogaster S2 cells