Acts as a component of the histone chaperone complex chromatin assembly factor 1 (CAF-1), which assembles histone octamers onto DNA during replication and repair. CAF-1 performs the first step of the nucleosome assembly process, bringing newly synthesized histones H3 and H4 to replicating DNA; histones H2A/H2B can bind to this chromatin precursor subsequent to DNA replication to complete the histone octamer. It may play a role in heterochromatin maintenance in proliferating cells by bringing newly synthesized cbx proteins to heterochromatic DNA replication foci. . This is the function of ENSG00000167670 (CHAF1A, chromatin assembly factor 1 subunit A).