Synovial sarcoma translocation protein SS18 (SS18)

Synovial sarcoma translocation protein SS18 is a core subunit of the BAF (BRG1/BRM-associated factor) chromatin remodeling complex (also known as SWI/SNF complex), which regulates gene expression by altering chromatin structure[2][3]. SS18 has a low-complexity, intrinsically disordered QPGY domain implicated in phase separation and epigenetic regulation[1]. In synovial sarcoma, a chromosomal translocation generates the oncogenic SS18-SSX fusion, which drives tumorigenesis through aberrant incorporation into BAF, altered complex specificity, and widespread misregulation of gene expression[1][2][3][4]. The wild-type SS18 protein interacts with BRG1 and other BAF subunits to mediate nucleosome remodeling, and structural characterization has revealed its formation of heterodimers and participation in dynamic liquid–liquid phase separation, highlighting its key roles in both normal cell physiology and cancer[1][2][3]. Misregulation of the BAF complex, including mutations or aberrant subunits such as SS18-SSX, is implicated not only in cancer but also in various neurological disorders[2][3][4].

Other names

SS18SYTSSXTsynovial sarcoma translocation proteinSS18 (imprecise historic: SYT, SSXT)

Potential mechanisms under investigation include disruption of SS18-SSX phase separation, inhibition of BAF complex assembly, and targeting synthetic lethal interactions in cancer cells