Acts as a component of chromatin assembly factor 1 (CAF- 1); which assembles histone octamers onto replicating DNA in vitro. It 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. p90 may facilitate the efficient and timely assembly of histones into telomeric chromatin.