Core histone-binding subunit that may target chromatin assembly factors, chromatin remodeling factors and histone deacetylases to their histone substrates in a manner that is regulated by nucleosomal DNA (By similarity). Plays a role in regulating cell cycle progression (PubMed:25446273). Required to repress the induction of vulval development by Ras signaling. In association with the zinc finger protein ztf-11, negatively regulates the expression of non-neuronal genes during neurogenesis (PubMed:31386623). Binds directly to helix 1 of the histone fold of histone H4, a region that is not accessible when H4 is in chromatin (By similarity). Interacts with zft-11; the interaction is required to suppress the activation of non-neuronal genes in neurons (PubMed:31386623). RNAi-mediated knockdown results in delayed cell cycle progression. Belongs to the WD repeat RBAP46/RBAP48/MSI1 family.