GP2 (glycoprotein 2), also known as ZAP75, is a 537 amino acid secreted protein that is expressed in pancreatic secretory (zymogen) granules, and is cleaved then released into the pancreatic duct along with exocrine secretions. GP2 interacts with syncollin and to type 1 fimbria of bacteria, a bacterial adhesin that is commonly expressed by members of the Enterobacteriacae family. Containing an EGF-like domain and a ZP domain, GP2 is also expressed on the apical plasma membrane of specialized microfold (M) cells among enterocytes and serves as a transcytotic receptor for mucosal antigens. M cells are considered a promising target for oral vaccination against various infectious diseases, and the GP2-dependent transcytotic pathway may provide a new target for the development of M-cell-targeted mucosal vaccines. GP2 exists as four alternatively spliced isoforms that are desginated isoform 1, isoform beta, isoform alpha and isoform 2.
