Abstract: Objective To find out the protein complex members associated with the nervous system polycomb 1 (NSPc1) in vivo. Methods Use the yeast two hybrid system to screen the potential interactive proteins of NSPc1, and verify the interaction by GST pull-down, co-immunoprecipitation and subcellular co-localization assays. Results The full length, N-terminus and C-terminus of NSPc1 were used as the "baits" to screen the 3-month fetal brain cDNA library in yeast. Some proteins, including HBO1 (Histone Acetyltransferase Binding to ORC-1), were found to be interactive proteins of NSPc1, then the interaction between HBO1 and NSPc1 was verified both in vitro and in vivo. Conclusion The histone acetyltransferase HBO1 is one of the interactive proteins of NSPc1, and the interaction may be involved in the epigenetic repression activity of polycomb proteins.