Updated project metadata. The Polycomb group (PcG) and Trithorax group (TrxG) proteins are key epigenetic regulators controlling silenced and active states of genes in multicellular organisms, respectively. In Drosophila PcG/TrxG proteins are recruited to chromatin via binding to specialized DNA-elements termed Polycomb Response Elements (PREs). While precise mechanisms of PcG/TrxG proteins recruitment remains unknown, the important role is suggested to belong to sequence specific DNA-binding factors. Here, using affinity purification coupled with high throughput mass spectrometry (IP/MS), we isolated factors associated with Combgap, Psq, Zeste and Adf1 PRE DNA-binding Drosophila proteins. As a control we used unspecific IgG. For affinity purification the nuclear extract from Drosophila S2 cells and polyclonal antibodies against Combgap, Psq, Zeste and Adf1 were used.