Shisa-4 (Shisa is a form of Japanese sculpture that involves faces/heads; also known as C1orf40, PRMP and TMEM58) is a 26-32kD member of the Shisa-4 subfamily, Shisa family of proteins. It may be found associated with the ER of embryonic limb bud cells, and based on other Shisa proteins, perhaps antagonizes either Wnt or FGF signaling. Shisa-4 is also described as a plasma membrane protein on oligodendroglia that links the ECM to the actin cytoskeleton. Mature human Shisa-4 is a 170 (aa) type I transmembrane protein. It contains a 60aa extracellular domain (aa28-87) plus an 89aa cytoplasmic region that possesses a Pro-rich segment (aa131-195). Over (aa29-85), human Shisa-4 shares 96% aa identity with mouse Shisa-4.