Helicase that possesses intrinsic ATP-dependent nucleosome-remodeling activity (By similarity). Catalytic subunit of ISWI chromatin-remodeling complexes, which form ordered nucleosome arrays on chromatin and facilitate access to DNA during DNA-templated processes such as DNA replication, transcription, and repair; this may require intact histone H4 tails (PubMed:11532953, PubMed:11980720, PubMed:12198165). Within the ISWI chromatin-remodeling complexes, slides edge- and center-positioned histone octamers away from their original location on the DNA template (PubMed:11532953, PubMed:11980720, PubMed:12198165). Catalytic activity and histone octamer sliding propensity is regulated and determined by components of the ISWI chromatin-remodeling complexes (By similarity). The BAZ1A/ACF1-, BAZ1B/WSTF-, BAZ2A/TIP5- and BAZ2B-containing ISWI chromatin-remodeling complexes regulate the spacing of nucleosomes along the chromatin and have the ability to slide mononucleosomes to the center of a DNA template in an ATP-dependent manner (PubMed:11532953, PubMed:11980720, PubMed:12198165). The CECR2- and RSF1-containing ISWI chromatin-remodeling complexes do not have the ability to slide mononucleosomes to the center of a DNA template (By similarity). Binds to core histones together with RSF1, and is required for the assembly of regular nucleosome arrays by the RSF-5 ISWI chromatin-remodeling complex (By similarity). Involved in DNA replication and together with BAZ1A/ACF1 is required for replication of pericentric heterochromatin in S-phase (By similarity). Probably plays a role in repression of RNA polymerase I dependent transcription of the rDNA locus, through the recruitment of the SIN3/HDAC1 corepressor complex to the rDNA promoter (PubMed:12198165). The WICH-5 ISWI chromatin-remodeling complex regulates the transcription of various genes, has a role in RNA polymerase I and RNA polymerase III transcription, mediates the histone H2AX phosphorylation at 'Tyr-142', and is involved in the maintenance of chromatin structures during DNA replication processes (PubMed:19092802). Essential component of the NoRC-5 ISWI chromatin-remodeling complex, a complex that mediates silencing of a fraction of rDNA by recruiting histone-modifying enzymes and DNA methyltransferases, leading to heterochromatin formation and transcriptional silencing (PubMed:11532953, PubMed:12198165, PubMed:12368916). Required for embryonic development and differentiation, and the proliferation of early blastocyst-derived stem cells (PubMed:14617767). Component of the ACF-5 ISWI chromatin-remodeling complex (also called the ACF/WCRF complex) at least composed of SMARCA5/SNF2H and BAZ1A/ACF1, which regulates the spacing of histone octamers on the DNA template to facilitate access to DNA (By similarity). Within the complex interacts with BAZ1A/ACF1; the interaction is direct and is required to slide nucleosomes from end to center positions on a DNA template in an ATP-dependent manner (By similarity). Component of the CHRAC ISWI chromatin-remodeling complex at least composed of SMARCA5/SNF2H, BAZ1A/ACF1, CHRAC1 and POLE3; the complex preferentially binds DNA through the CHRAC1-POLE3 heterodimer and possesses ATP-dependent nucleosome-remodeling activity (By similarity). Within the complex interacts with BAZ1A/ACF1; the interaction is direct and promotes the interaction with the POLE3-CHRAC1 heterodimer (By similarity). Within the complex interacts with the POLE3-CHRAC1 heterodimer; the interaction is direct and enhances nucleosome sliding activity by the SMARCA5/SNF2H and BAZ1A/ACF1 interaction (By similarity). Neither POLE3 nor CHRAC1 enhances nucleosome sliding activity of the ACF-5 ISWI chromatin remodeling complex (By similarity). Component of the WICH-5 ISWI chromatin-remodeling complex (also called the WICH complex) at least composed of SMARCA5/SNF2H and BAZ1B/WSTF, which regulates the spacing of histone octamers on the DNA template to facilitate access to DNA (PubMed:11980720). Within the complex interacts with BAZ1B/WSTF (PubMed:19092802). Component of the NoRC-5 ISWI chromatin-remodeling complex (also called the NoRC chromatin-remodeling complex) at least composed of SMARCA5/SNF2H and BAZ2A/TIP5; the complex suppresses rDNA transcription by a combination of nucleosome remodeling, histone deacetylation, and DNA methylation (PubMed:11532953, PubMed:12198165). Within the complex interacts with BAZ2A/TIP5 (PubMed:12198165). Within the complex interacts with HDAC1 (PubMed:12198165). Component of the BRF-5 ISWI chromatin-remodeling complex at least composed of SMARCA5/SNF2H and BAZ2B (By similarity). Within the complex interacts with BAZ2B (By similarity). Component of the NURF-5 ISWI chromatin-remodeling complex at least composed of SMARCA5/SNF2H and BPTF (By similarity). Within the complex interacts with BPFT (By similarity). Component of the CERF-5 ISWI chromatin-remodeling complex at least composed of SMARCA5/SNF2H and CECR2 (By similarity). Within the complex interacts with CECR2 (By similarity). Component of the RSF-5 ISWI chromatin-remodeling complex (also called the RSF complex) at least composed of SMARCA5/SNF2H and RSF1 (By similarity). Within the complex interacts with RSF1 (By similarity). Interacts with the cohesin complex component RAD21; the interaction is direct (By similarity). Interacts with the NuRD complex components HDAC2, RBBP4 and CHD4; the interactions are direct (By similarity). Interacts with PCNA (By similarity). Component of the B-WICH complex, at least composed of SMARCA5/SNF2H, BAZ1B/WSTF, SF3B1, DEK, MYO1C, ERCC6, MYBBP1A and DDX21 which positively regulates RNA polymerase III transcription (By similarity). Interacts with MYO1C (PubMed:16514417). Interacts with BEND3 (By similarity). Interacts with SIRT6; promoting recruitment to DNA damage sites (By similarity). Localizes to mitotic chromosomes. Co-localizes with RSF1 in the nucleus. Co-localizes with PCNA at replication foci during S phase. Co-localizes with BAZ1B/WSTF at replication foci during late-S phase. Recruited to DNA damage sites following interactiuon with SIRT6. Ubiquitously expressed. Expressed in CD34-positive erythrocyte progenitor cells. Down-regulated upon differentiation. Belongs to the SNF2/RAD54 helicase family. ISWI subfamily. Truncated N-terminus.