CD326/EpCAM

EpCAM, the CD326 antigen formerly known as the 17-1A antigen (TACSTD1), is a 30-40 kDa type I transmembrane glycoprotein composed of an epidermal growth factor-like domain, two thyroglobulin repeat domains and a short cytoplasmic tail. It mediates calcium-independent epithelial cell adhesion and is normally confined to basolateral membranes of simple and stratified epithelia. EpCAM is overexpressed in the majority of epithelial carcinomas, which underpins its use for circulating tumor cell enrichment and as the target of catumaxomab and other antibody formats. Its intracellular domain undergoes regulated intramembrane proteolysis, releasing a fragment with transcriptional activity.