Ubn1 and Ubn2 are essential subunits of the Histone Regulator A (HiRA) complex, the H3.3 histone variant chaperone for euchromatin. We pulled-down Ubn1 and Ubn2 with a C-terminal AVI-tag in mouse embryonic stem cells and identified, besides all known components of the complex, transcription factors that may play a role in the recruitment of HiRA to chromatin.