SSX1/3 (E9P5M) Rabbit mAb (Amino-terminal Antigen) #42734

The SS18-SSX fusion proteins are a result of in-frame fusions that fuse the SS18 gene on chromosome 18 with X chromosome genes SSX1, SSX2, and to a lesser extent SSX4 (1). Human synovial sarcoma (SS) accounts for 8-10% of all soft tissue malignancies and 95% of these malignancies express the recurrent translocation of the SS18 gene on chromosome 18 (1). The N-terminal SNH domain (SYT N-terminal homology domain) of the SS18 protein interacts with SWI/SNF chromatin remodeling complexes via the N terminal region of BRM and BRG1 subunits (2). Studies of the SS18-SSX fusion in SS suggest that endogenous SS18 competes with the mutant SS18-SSX fusion for occupancy in the SWI/SNF complexes resulting in the displacement of the SNF5 (BAF47) subunit. Displacement of the SNF5 subunit results in altered function of the SWI/SNF complex that leads to deregulated expression of genes such as Sox2 in SS (1).

While the SSX family of proteins is well characterized in SS, little is known outside of this context. The conserved N-terminus of the SSX family contains a KRAB domain which seems to function as a transcriptional repressor (3).