Histone chaperone that facilitates histone deposition and histone exchange and removal during nucleosome assembly and disassembly (PubMed:16936140, PubMed:16678113, PubMed:16407267, PubMed:16039596, PubMed:15891116, PubMed:16303565, PubMed:15766286, PubMed:15542829, PubMed:15175160, PubMed:15452122, PubMed:15071494, PubMed:11856374, PubMed:11404324, PubMed:11331602, PubMed:11172707, PubMed:14680630). Facilitates histone deposition through both replication-dependent and replication-independent chromatin assembly pathways (PubMed:14585955, PubMed:16678113, PubMed:15632066). Cooperates with chromatin assembly factor 1 (CAF-1) to promote replication-dependent chromatin assembly and with the HIR complex to promote replication-independent chromatin assembly, which may occur during transcription and DNA repair (PubMed:16501045, PubMed:16582440, PubMed:16141196, PubMed:16143623, PubMed:16020781, PubMed:15821127, PubMed:16303565, PubMed:15542840, PubMed:12093919, PubMed:11756556, PubMed:11404324, PubMed:11731480, PubMed:11731479, PubMed:11412995, PubMed:10591219). May be required for the maintenance of a subset of replication elongation factors, including DNA polymerase epsilon, the RFC complex and PCNA, at stalled replication forks (PubMed:15901673, PubMed:11412995). Also required for RTT109-dependent acetylation of histone H3 on 'Lys-9' and 'Lys-56' (PubMed:17320445, PubMed:17107956, PubMed:17046836, PubMed:16815704, PubMed:16627621, PubMed:15840725, PubMed:21256037). Promotion of RTT109-mediated histone H3 'Lys-56' acetylation is dependent on interactions with histone H3 pre-acetylated on 'Lys-14' (PubMed:31194870). Interacts with histone H3/H4 heterodimers via both histone H3 and histone H4 (PubMed:11172707, PubMed:11412995, PubMed:11856374, PubMed:11756556, PubMed:12626510, PubMed:16303565, PubMed:15840725, PubMed:16582440, PubMed:14680630, PubMed:17081973, PubMed:31387991, PubMed:29300933, PubMed:27036862). Binds with higher affinity to H3/H4 heterodimers where histone H3 has been pre-acetylated on 'Lys-14' (PubMed:31194870). Interacts with RAD53 and this may impair interaction with histones and chromatin assembly; the interaction is reduced upon activation of DNA damage or replication checkpoints which in turn promotes histone binding and chromatin assembly (PubMed:11331602, PubMed:12851493, PubMed:12917350, PubMed:16303565, PubMed:16020781, PubMed:14680630). Interacts with the CAC2 subunit of chromatin assembly factor 1 (CAF-1) (PubMed:11756556). Interacts with the HIR1, HIR2, HIR3 and HPC2 subunits of the HIR complex (PubMed:11404324, PubMed:11412995, PubMed:16303565). Interacts with the RFC1, RFC2, RFC3, RFC4 and RFC5 subunits of the replication factor C (RF-C/RFC) complex; which may recruit this protein to DNA (PubMed:15901673). Interacts with the SAS2, SAS4 and SAS5 subunits of the SAS/SAS-I complex (PubMed:11731479, PubMed:11731480). Interacts with the BDF1, BDF2, SPT15, TAF1 and TAF7 subunits of the TFIID complex (PubMed:12093919). Interacts with RTT109 and VPS75; the interaction with RTT109 is direct (PubMed:29300933, PubMed:31387991, PubMed:17320445). Expression peaks in S-phase (at the RNA level). Present with 6230 molecules/cell in log phase SD medium. Belongs to the ASF1 family.