YY1 physically interacts with cohesin complex proteins through its zinc finger domain. (A-B) YY1 physically interacts with cohesin complex proteins in 293 cells. (A) Nuclear extracts were immunoprecipitated with anti-Flag antibody and were western blotted for SMC1A, SMC3, RAD21, YY1, or Flag. (B) Reciprocal nuclear co-immunoprecipitation (co-IP). Nuclear extracts were immunoprecipitated with anti-SMC3 antibody and western blotted for SMC3, Flag, or YY1. (C-D) YY1 physically interacts with cohesin complex proteins in HPC7. (C) Nuclear extracts were immunoprecipitated with anti-Flag antibody and were western blotted for SMC1A, SMC3, RAD21, Flag or YY1. (D) Reciprocal nuclear co-IP. Nuclear extracts were immunoprecipitated with anti-SMC3 antibody and western blotted for SMC3, Flag, or YY1. (E) Endogenous YY1 physically interacts with SMC3 in 5-fluorouracil enriched BMCs. Nuclear extracts of 5-fluorouracil–enriched BMCs from C57BL/6 mice were immunoprecipitated with anti-YY1 or anti-SMC3 antibody and were western blotted for SMC3 or YY1. (F) Diagram of YY1 functional domain and YY1 mutants. (G) YY1 amino acid sequence 298 through 414 is required for its physical interaction with SMC3. Nuclear extracts from transfected cells were immunoprecipitated with anti-Flag antibody and western blotted for SMC3, CTCF, or Flag.