Figure 1: Chemical dimerization to induce chromatin-associated condensates.

(A) Dimerization schematic: The dimerizer consists of two linked ligands, TMP and Halo that interact with eDHFR and Haloenzyme, respectively. The phase separating protein is fused to mCherry and eDHFR, and the chromosome anchor protein is fused to Halo and GFP. (B) Before adding dimerizer (top left nucleus), the majority of chromosome anchor proteins (green squares) are localized to the chromosomes and a small amount of anchor proteins are diffusely localized in the nucleoplasm. Phase separating proteins to be recruited (purple stars) and phase separating partners (proteins that will condense with the phase separating protein, red triangles) are diffusely localized in the nucleoplasm. After adding dimerizers (top right nucleus), phase separating proteins are dimerized to the anchor protein on the chromosomes and in the nucleoplasm. There could be some excess phase separating proteins in the nucleoplasm, depending on the relative concentration of the anchor protein, phase separating protein and the dimerizer used. After dimerization (bottom right nucleus), increased local concentration of the phase separating proteins at the anchor leads to phase separation and the formation of chromatin-associated condensates. Phase separating partners are enriched at the anchor because of co-condensation with the eDHFR-fused phase separating protein. Anchor proteins that are not directly bound to the chromatin can be enriched at the anchor because of dimerization to the phase separating protein. After adding excess free TMP to compete with the dimerizer for eDHFR binding (bottom left nucleus), the phase separating protein is released from the chromatin and the condensate is dissolved.