Trop-2 (TACSTD2) is a transmembrane glycoprotein found on invasive trophoblast cells and in several epithelial type cancer cells. Trop-2 has an extracellular domain with EGF thyroglobulin type-1 repeats, a transmembrane domain and a short cytoplasmic tail with a HIKE domain containing a PIP2 binding site. This glycoprotein functions in many signaling pathways including interaction of its extracellular domain with integrin beta1 to regulate FAK signaling, interaction of its transmembrane domain with claudin 1 and claudin 7 during tight junction formation, and regulation of intracellular calcium release by its PIP2 binding and activation of the ERK/MAPK pathway. These Trop-2 functions may be important during tumor proliferation, metastasis and invasion.
