The present invention is directed to the identification of a biomarker specifically located in the plasma membrane of pancreatic beta cells. It was selected by a Systems Biology approach on Massively Parallel Signal Sequencing datasets obtained in human islets and Affymetrix microarray datasets on human islets, purified rat primary beta and non beta cells and insulinoma cells. Based on a set of specific features the biomarker is a unique candidate for imaging and targeting strategies to study the pancreatic beta cell mass in health and disease (T1 D, T2D, pancreatic cancers, obesity, islet transplantation, beta cell regeneration). The five specific features of the selected biomarkers are: 1) Preferentially expressed in pancreatic islets as compared to surrounding tissues 2) Higher expression in pancreatic beta cells than in pancreatic alpha cells or than in other islet non-beta cells 3) Expression levels in pancreatic beta cells are higher or comparable to glucokinase which is an enzyme specifically expressed in the pancreatic beta cell 4) Located in the membrane and as such targetable with antibodies, peptides or small molecules which allows imaging, targeting and immunohistochemistry and 5) Expression is not induced during the process of inflammation of the beta cell mass and the protein is not enriched in T-cells and dendritic cells or in other cells participating in the inflammation process.
