| Domain/motif | Approx. location if available | Molecular role | Key experimental evidence / quantitative data | Key citations (with DOI URL) |
|---|---|---|---|---|
| HSA (helicase-SANT-associated) | N-terminal; exact residues not given in provided context | Binds actin-related proteins Arp7 and Arp9; helps build the SWI/SNF motor/ARP module | Experimental summaries report HSA is required for Arp7/Arp9 association with Snf2; ARP association contributes >90% of catalytic activity in one mechanistic summary of yeast SWI/SNF (pqac-00000001, pqac-00000004) | Sen et al., 2011-08, *Nucleic Acids Res.* DOI: https://doi.org/10.1093/nar/gkr622; mechanistic review/summary in provided context, year not stated (pqac-00000001) |
| QLQ | Between N-terminus and HSA | Conserved domain present in Snf2 architecture; specific function not established in the provided evidence | Domain is explicitly noted as conserved in yeast Snf2, but no direct functional assay or quantitative phenotype for QLQ is described in the retrieved context (pqac-00000004) | Sen et al., 2011-08, *Nucleic Acids Res.* DOI: https://doi.org/10.1093/nar/gkr622 |
| pHSA | Between HSA and ATPase region (exact residues not given) | Links ARP module to ATPase; conformational coupling on ARP binding | Mechanistic summary states pHSA connects HSA/ARP binding to the ATPase region and changes conformation upon ARP association, supporting motor regulation; no residue-level quantitative assay provided in retrieved context (pqac-00000001) | Mechanistic review/summary in provided context, year not stated (pqac-00000001) |
| ATPase / DNA translocase helicase motifs | Central motor; seven helicase motifs noted | Catalyzes ATP hydrolysis and DNA translocation on nucleosomes; powers nucleosome sliding, unwrapping, rewrapping, histone ejection/displacement | Snf2 is the catalytic subunit of SWI/SNF and a DNA-dependent ATPase whose optimal substrate is nucleosomal DNA rather than naked DNA; SWI/SNF activities summarized include nucleosome mobilization/displacement, sliding, and histone ejection. Recent review table identifies yeast Snf2 as the SWI/SNF motor ATPase with distal acidic-patch binding and bromodomain features (pqac-00000001, pqac-00000002, pqac-00000003, pqac-00000007) | Sen et al., 2011-08, *Nucleic Acids Res.* DOI: https://doi.org/10.1093/nar/gkr622; Eustermann et al., 2024-12, *Nat. Rev. Mol. Cell Biol.* DOI: https://doi.org/10.1038/s41580-023-00683-y |
| SnAC (Snf2 ATP coupling) | Between ATPase and AT-hook; deletion tested for aa1312–1444 | Couples ATP hydrolysis to remodeling; positively regulates ATPase output without major effect on ATP affinity or nucleosome binding | Deletion/mutation severely impairs ATPase and nucleosome mobilization, but not complex integrity or nucleosome binding. WT versus ΔSnAC nucleosome KD values are similar (2.85 ± 0.5 nM vs 2.38 ± 0.7 nM), supporting a catalytic-coupling rather than binding role. ΔSnAC expression profile correlates strongly with snf2Δ (r = 0.88), indicating essentiality for most Snf2-dependent gene activation (pqac-00000003, pqac-00000005, pqac-00000006) | Sen et al., 2011-08, *Nucleic Acids Res.* DOI: https://doi.org/10.1093/nar/gkr622 |
| AT-hook(s) | C-terminal region; ΔAT deletion spans ~aa1446–1530 in one assay set | Auto-regulatory domain that stimulates DNA- and nucleosome-stimulated ATPase activity, promotes nucleosome engagement, and supports in vivo SWI/SNF function | 2023 study shows ΔAT lowers ATPase Vmax ~13-fold on DNA (0.795 to 0.0604 μM/min) and ~14-fold on nucleosomes (4.19 to 0.301 μM/min), with modest DNA KM change (311 to 340 nM) but much worse nucleosome KM (98 to 364 nM). Binding effects are smaller but detectable: free DNA KD 7.87 vs 12.8 nM; nucleosome KD 7.67 vs 20.5 nM. Crosslinking places AT-hooks near H3 K15/K28, SnAC, and ATPase C-lobe. Growth assays indicate requirement for amino-acid biosynthesis/stress responses and ethanol metabolism, while some carbon-source switching phenotypes are less dependent on AT-hooks (pqac-00000008, pqac-00000009, pqac-00000010, pqac-00000011, pqac-00000012, pqac-00000022, pqac-00000023) | Saha et al., 2023-08, *Nat. Commun.* DOI: https://doi.org/10.1038/s41467-023-40386-8 |
| Bromodomain | C-terminal | Recognizes acetylated histone tails; contributes to chromatin targeting/retention and remodeler dynamics on acetylated chromatin | The bromodomain is reported to bind acetylated N-terminal histone tails. Mechanistic summary notes stimulation by tetra-acetylated H3 and acetyl-H3/H4 recognition. Recent work on stress-responsive genes showed competitive bromodomain interactions regulate Swi/Snf recruitment/release dynamics, including effects of Snf2 acetylation on binding to acetylated nucleosomes (pqac-00000001, pqac-00000004) | Sen et al., 2011-08, *Nucleic Acids Res.* DOI: https://doi.org/10.1093/nar/gkr622; Dutta et al., 2014-10, *Genes Dev.* DOI: https://doi.org/10.1101/gad.243584.114 |
| N-terminal activator-binding domain (ABD) | aa238–307 | Direct interaction with transcriptional activator TADs; likely contributes to recruitment but is dispensable in vivo because of redundancy with other SWI/SNF subunits | 2024 mapping study identified a ~70-aa Swi2 ABD (aa238–307) that binds Ino2 TAD1/TAD2 and also TADs from Gal4, Gcn4, Rap1, Aro80, and Swi5. In vivo, deletion variants lacking the ABD complemented swi2Δ growth phenotypes, indicating dispensability/redundancy. In reporter assays, Ino2 TAD1 activation dropped to 13.4% in swi2 null cells, whereas TAD2 retained 72.5%, supporting selective recruitment contributions (pqac-00000016, pqac-00000017, pqac-00000018, pqac-00000019) | Wendegatz et al., 2024-09, *Current Genetics* DOI: https://doi.org/10.1007/s00294-024-01300-x |


*Table: This table summarizes the experimentally supported domain architecture of Saccharomyces cerevisiae Snf2/Swi2 (UniProt P22082; YOR290C), emphasizing what each motif contributes to SWI/SNF remodeling. It highlights where the evidence is strong and quantitative, especially for the SnAC and AT-hook regions.*