EpCAM (epithelial cell adhesion molecule), a stem and carcinoma cell marker, is a cell surface protein involved in homotypic cell-cell adhesion via intercellular oligomerization and proliferative signalling via proteolytic cleavage. Structure analysis indicate that it is composed of three domains: N-domain, Thyroglobulin type-1A (TY) domain and the C-terminal domain. This entry represents the small and compact disulphide-rich N-terminal domain of 39 amino-acid residues [1]. Trop-2 (also known as tumor-associated calcium signal transducer 2, TACSTD2) is also included in this entry, as they are evolutionarily related and both are implicated in signaling triggered by proteolytic cleavage within the ectodomain [1-3]. They share an overall similar structure but differ in their dimers formation.

1: Crystal structure and its bearing towards an understanding of key biological functions of EpCAM. Pavsic M, Guncar G, Djinovic-Carugo K, Lenarcic B; Nat Commun. 2014;5:4764. PMID:25163760

2: Biochemical and preliminary X-ray characterization of the tumor-associated calcium signal transducer 2 (Trop2) ectodomain. Vidmar T, Pavsic M, Lenarcic B; Protein Expr Purif. 2013;91:69-76. PMID:23872121

3: Trop2 Forms a Stable Dimer with Significant Structural Differences within the Membrane-Distal Region as Compared to EpCAM. Pavsic M; Int J Mol Sci. 2021; [Epub ahead of print] PMID:34638982