核小体改构复合体(Nucleosome remodeling complex)是一类是具有DNA激活的ATP酶活性的复合体，它们通过重构核小体的组蛋白核心或改变DNA 链在核小体上的位置来增加启动子串行与转录因子的可接触性，从而激活基因转录。

另一类是组蛋白乙酰转移酶家族（HATs），可以对核心组蛋白N-端尾巴上的赖氨酸残基进行乙酰化修饰，以此调节基因转录。

The protein ISWI or imitation SWI of drosophila melanogaster (common fruit fly), is the first ATPase subunit which has been isolated in the ISWI chromatin remodeling family. This protein presents high level of similarity to the SWI/SNF chromatin remodeling family in the ATPase domain. Outside the ATPase domain ISWI loses the similarity with the member of the SWI/SNF family, possessing a SANT domain instead of the bromodomain. The protein ISWI can interact with several proteins giving three different chromatin-remodeling complexes in Drosophila melanogaster: NURF(nucleosome remodeling factor), CHRAC (chromatin remodeling and assembly complex) and ACF (ATP-utilising chromatin remodeling and assembly Factor).