Required for the periodic repression of histone gene transcription during the cell cycle (By similarity). Required for replication-independent chromatin assembly. Promotes remodeling of sperm chromatin following fertilization via the incorporation of histone H3.3 and histone H4. Maternally contributed protein localizes specifically to the male nucleus in fertilized eggs. This localization persists from the initiation of sperm nucleus decondensation to the end of pronucleus formation. Expressed maternally and zygotically throughout development to adults (male and female). Belongs to the WD repeat HIR1 family. Was originally thought to be involved in protamine removal but this was shown to be incorrect in the subsequent published erratum.