Involved in transcriptional regulation and chromatin remodeling. Facilitates DNA replication in multiple cellular environments and is required for efficient replication of a subset of genomic loci. Binds to DNA tandem repeat sequences in both telomeres and euchromatin and in vitro binds DNA quadruplex structures. May help stabilizing G-rich regions into regular chromatin structures by remodeling G4 DNA and incorporating H3.3-containing nucleosomes. Catalytic component of the chromatin remodeling complex ATRX:DAXX which has ATP-dependent DNA translocase activity and catalyzes the replication-independent deposition of histone H3.3 in pericentric DNA repeats outside S-phase and telomeres, and the in vitro remodeling of H3.3-containing nucleosomes. Its heterochromatin targeting is proposed to involve a combinatorial readout of histone H3 modifications (specifically methylation states of H3K9 and H3K4) and association with CBX5. May be involved in transcriptional regulation of telomeric repeat-containing RNA (TERRA). Acts as negative regulator of chromatin incorporation of transcriptionally repressive histone MACROH2A1, particularily at telomeres. Binds to zinc-finger coding genes with atypical chromatin signatures and regulates its H3K9me3 levels. Forms a complex with ZNF274, TRIM28 and SETDB1 to facilitate the deposition and maintenance of H3K9me3 at the 3' exons of zinc-finger genes (By similarity). ATP + H2O = ADP + H(+) + phosphate Interacts with DAXX to form the chromatin remodeling complex ATRX:DAXX. Probably binds EZH2. Binds annexin V in a calcium and phosphatidylcholine/phosphatidylserine-dependent manner. Interacts directly with CBX5 via the PxVxL motif. Interacts with RAD50, MRE11 and NBN; indicative for an association with the MRN complex. Interacts with histone MACROH2A1. Interacts with histone H3 peptides methylated at 'Lys-10' with preferences H3K9me3 > H3K9me2 > H3K9me1. Interacts with histone H3 peptides unmethylated at 'Lys-5' (H3K4me0). Interacts with MECP2, SMC1 and SMC3. Interacts with SETDB1, TRIM28 and ZNF274 (By similarity). Associated with pericentromeric heterochromatin during interphase and mitosis, probably by interacting with CBX5/HP1 alpha. Colocalizes with histone H3.3, DAXX, HIRA and ASF1A at PML-nuclear bodies (By similarity). Expressed in all tissues except developing testis. The ADD domain predominantly interacts with histone H3 trimethylated at 'Lys-10'(H3K9me3) (and to a lesser extent H3 mono- or dimethylated at 'Lys-10') and simultanously to histone H3 unmethylated at 'Lys-5' (H3K4me0). The interaction with H3K9me3 is disrupted by the presence of H3K4me3 suggesting a readout of the combined histone H3 methylation state (By similarity). Belongs to the SNF2/RAD54 helicase family.