RSC (Remodeling the Structure of Chromatin) is a member of the ATP-dependent chromatin remodeler family. The activity of the RSC complex allows for chromatin to be remodeled by altering the structure of the nucleosome. There are four subfamilies of chromatin remodelers: SWI/SNF, INO80, ISW1, and CHD. The RSC complex is a 15-subunit chromatin remodeling complex initially found in Saccharomyces cerevisiae, and is homologous to the SWI/SNF complex found in humans. The RSC complex has ATPase activity in the presence of DNA. RSC Complex vs. SWI/SNF While RSC and SWI/SNF are considered homologous, RSC is significantly more common than the SWI/SNF complex and it is required for mitotic cell division. Without the RSC complex, cells would not survive. RSC consists of 15 subunits, and at least three of these subunits are conserved between RSC and SWI/SNF. RSC and SWI/SNF are composed of very similar components, such as the Sth1 components in RSC and the SWI2/Snf2p in SWI/SNF. Both of these components are ATPases that consist of Arp7 and Arp9, which are proteins that are similar to actin. The subunits of Sth1 (Rsc6p, Rsc8p, and Sfh1p) are paralogues to the three subunits of SWI/SNF (Swp73p, Swi3p, and Snf5p). While there are many similarities between these two chromatin remodeling complexes, they remodel different parts of chromatin. They also have opposing roles, specifically when interacting with the PHO8 promoter. RSC works to guarantee the placement of nucleosome N-3, while SWI/SNF attempts to override the placement of N-3. RSC and SWI/SNF complexes both function as chromatin remodeling complexes in humans (Homo sapiens) and the common fruit fly (Drosophila melanogaster). SWI/SNF was first discovered when a genetic screen was done in yeast with a mutation causing a deficiency in mating-type switching (swi) and a mutation causing a deficiency in sucrose fermentation. After this chromatin remodeling complex was discovered, the RSC complex was found when its components, Snf2 and Swi2p, were discovered to be homologous to the SWI/SNF complex. Due to research done using BLAST (biotechnology), it is believed that the yeast RSC complex is even more similar to the human SWI/SNF complex than it is to the yeast SWI/SNF complex. The Role of RSC The role of nucleosomes is a very important topic of research. It is known that nucleosomes interfere with the binding of transcription factors to DNA, therefore they can control transcription and replication. With the help of an in vitro experiment using yeast,