Histone chaperone that facilitates histone deposition and histone exchange and removal during nucleosome assembly and disassembly (PubMed:11897662, PubMed:14718166, PubMed:15664198, PubMed:16151251, PubMed:21454524, PubMed:26527279). Cooperates with chromatin assembly factor 1 (CAF-1) to promote replication-dependent chromatin assembly (PubMed:11897662, PubMed:14718166, PubMed:15664198, PubMed:16151251). 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 (H4K5K12ac) marks in the cytosol (PubMed:20953179, PubMed:21454524, PubMed:26527279). Does not participate in replication-independent nucleosome deposition which is mediated by ASF1A and HIRA (PubMed:11897662, PubMed:14718166, PubMed:15664198, PubMed:16151251). Required for gonad development (PubMed:12842904).