In molecular biology, SWI/SNF (SWItch/Sucrose Non-Fermentable),[1][2] is a subfamily of ATP-dependent chromatin remodeling complexes, which is found in eukaryotes.

[3] It possesses a DNA-stimulated ATPase activity that can destabilize histone-DNA interactions in reconstituted nucleosomes in an ATP-dependent manner, though the exact nature of this structural change is unknown.

The movement of nucleosomes provides easier access to the chromatin, enabling binding of specific transcription factors,[4] and allowing genes to be activated or repressed.

[11] A recent study[12] has provided strong evidence against the twist diffusion mechanism and has further strengthened the loop-recapture model.

[13] Early studies identified that SWI/SNF subunits were frequently absent in cancer cell lines.

[19][20][21][22] Several studies revealed that subunits of the mammalian complex, including ARID1A,[23] PBRM1,[22] SMARCB1,[24] SMARCA4,[25] and ARID2,[20] are frequently mutated in human cancers.

Small molecules that inactivate SWI/SNF complexes by interfering with ATP hydrolysis[30][38] or by causing degradation of key protein subunits[39] have demonstrated efficacy in pre-clinical studies.

[46] A model of the mammalian ATPase SMARCA4 shows similar features,[25] based on the high degree of sequence homology with yeast Snf2.

The interface between two subunits, BAF155 (SMARCC1) and BAF47 (SMARCB1) was also resolved, providing important insights into the mechanisms of the SWI/SNF complex assembly pathway.

It has ATPase activity, meaning it breaks down ATP, the basic unit of energy currency.

It was named after initially screening for mutations that would affect the pathways for both yeast mating types switching (SWI) and sucrose non-fermenting (SNF).