BAF53b is a member of a family of actin-related proteins (ARPs), which shares significant sequence identity with conventional actins. Both actins and ARPs comprise an actin fold, which forms an ATP binding cleft. BAF53b is a component of the BAF (BRG/brm-associated factor) complex in mammals, which is functionally related to the SWI/SNF complex in S. cerevisiae and Drosophila, and is associated with chromatin remodelling to facilitate transcriptional activation. As neural progenitors exit the cell cycle, the highly homologous BAF53a subunit of the BAF complex is replaced by BAF53b. This subunit switch is essential for the transition from from neural stem cells / progenitors to postmitotic neurons. BAF53b also plays a role in dendritic outgrowth, during which it is required to recruit the BAF complex and the dendritic regulator CREST to specific gene promoters. This function can not be performed by BAF53a.