GP2 (pancreatic zymogen granule membrane glycoprotein 2, ZAP75) is a protein found in great abundance in the pancreatic secretory granule membrane that is involved in regulating the innate immune response, is capable of sensing microbiota and is thought to function to prevent binding of bacteria to host epithelial cells. It is released into the intestine after being cleaved from the secretory granule membrane in the pancreas. It is a receptor for type 1 fimbriae (T1F) protein expressing bacteria such as Salmonella and Escherichia coli. It is expressed on multipotent progenitor cells in the developing pancreas. It is thus considered to be a useful cell-surface biomarker for embryonic pancreatic progenitors in vivo, with utility in the purification of embryonic stem cell-derived progenitors or in the evaluation of pancreatic differentiation in vitro. In immunohistochemistry, GP2 has cytoplasmic positivity in the pancreas as well as secretory positivity in the intestine and other tissues. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804; Front. Microbiol. 2018, DOI:10.3389/fmicb.2018.01905; Nat Commun 8, 331 (2017), DOI:10.1038/s41467-017-00561-0; J Immunol. 2012 Sep 15;189(6):2774-83, PMID: 22891285;