Histone chaperone that facilitates histone deposition and histone exchange and removal during nucleosome assembly and disassembly. Cooperates with chromatin assembly factor 1 (CAF-1) to promote replication-dependent chromatin assembly. Also involved in the nuclear import of the histone H3-H4 dimer together with importin-4 (IPO4): specifically recognizes and binds newly synthesized histones with the monomethylation of H3 'Lys-9' (H3K9me1) and diacetylation at 'Lys-5' and 'Lys-12' of H4 (H4K5ac and H4K12ac) marks in the cytosol. Does not participate in replication-independent nucleosome deposition which is mediated by ASF1A and HIRA. Required for gonad development. Interacts with histone H3 (including both histone H3.1 and H3.3) and histone H4. Interacts with the CHAF1A, CHAF1B and RBBP4 subunits of the CAF-1 complex. Interacts with HAT1, NASP and TAF1. Interacts with CDAN1. Found in a cytosolic complex with CDAN1, ASF1A, IPO4 and histones H3.1 and H4. Interacts with CREBBP. Phosphorylated by TLK1 and TLK2. Belongs to the ASF1 family.