Histones H3 and H4 chaperone involved in the nucleosome formation and heterochromatin silencing. Required for the deposition of H3K56ac-carrying H3-H4 complex onto newly-replicated DNA. Plays a role in the transcriptional regulation of the cell-cycle dependent histone genes by creating a repressive structure at the core histone gene promoter (By similarity). Interacts with histones H3 and H4. Belongs to the RTT106 family.