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). Required for hcp-3 and his-1 stabilization, localization of hcp-3 to centromeres and for proper chromosome segregation (PubMed:25446273, PubMed:26904949). Synthetic multivulva class B (synMuvB) protein (PubMed:9875852). SynMuvB proteins are required to repress the induction of vulval development by Ras signaling and probably act by forming the multiprotein DRM complex that represses transcription (PubMed:10704416, PubMed:17075059, PubMed:9875852). 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). Probable component of a NuRD-like complex, composed of at least lin-53 and hda-1 (PubMed:17075059). Interacts with lin-35 (PubMed:9875852). Interacts with hda-1; the interaction is direct (PubMed:9875852, PubMed:17075059). Component of the DRM complex, at least composed of lin-9, lin-35, lin-37, lin-52, lin-53, lin-54- dpl-1 and efl-1 (PubMed:17075059). Interacts with hcp-3 (PubMed:26904949). Localizes to centromeres during metaphase. Requires hcp-3 and knl-2 for nuclear and centromere localization. Ubiquitously expressed in embryos and newly hatched larvae. Expressed in all P(3-8).p vulval precursor cells at the time of vulval induction and until after all cell divisions and vulval morphogenesis are complete. Decreased protein levels of DRM complex components including lin-9, lin-37, lin-52 and lin-54 (PubMed:17075059). Double knockout with the programmed cell death regulator mcd-1 results slow larval growth (PubMed:17237514). RNAi-mediated knockdown results in embryonic lethality (PubMed:9875852, PubMed:26904949). RNAi-mediated knockdown leads to a reduction of hcp-3 and his-1 protein levels and to a depletion of hcp-3 on centromeres and a reduction of H3K27me3 levels on metaphase chromosomes (PubMed:26904949). RNAi-mediated knockdown results in chromosome segregation defects during mitosis (PubMed:25446273, PubMed:26904949). Belongs to the WD repeat RBAP46/RBAP48/MSI1 family.