The incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagons-like peptide-1 (GLP-1), are a group of gastrointestinal hormones that cause an increase in the amount ofinsulin released from the beta cells ofthe islets of Langerhans after ingestion of food.The intestinal peptide GIP was first isolated from porcine upper small intestine1). The sequences ofporcine, bovineand human GIPhave been determined, each has 42 amino acids, and thesequencesis highly conserved. The porcine and bovine peptides differ from the human at two and three site,respectively. Takeda et al. have isolated a human cDNA encoding the GIP precursor and confirming thatGIP belongs to the vasoactive intestinal peptide (VIP)/Glucagon/secretin family.GIP is a gastrointestinal peptide hormone that is released from duodenal endocrine K cells after absorption ofglucose or fat. GIP is a potent releaser of insulin in experimental animals8) and in man 9,10) providedthat the blood glucose is above basal level. Plasma level of GIP is elevated after an oral glucose load or ameal in normal man. This increase after a meal is below normal in newly diagnosed insulindependentdiabetics).It is now being recognized that GIP receptor is also expressed in organs and cells such asduodenum, small intestine, pancreatic alpha-cell, adipocyte and osteoblast. These results demonstrateGIP may have a lot of physiological effect inaddition to their glucoregulatory effects.GIP is rapidly inactivated by the enzyme dipeptidyl peptidase- 4 (DPP- 4) to GIPwith a bloodhalf-life of only several minutes. DPP- 4 inhibitor can prolong the half-life of GIP, that expectingtreatment of incretin effect.The kit can be used for measurement of total GIP [both GIP (1-42) and GIP (3-42)] in human plasmawith high sensitivity. It will be a specifically useful tool for incretin research.This ELISA kit is used for quantitative determination of human total GIP in plasma and culture mediumsupernatant. The kit is characterized by its sensitive quantification and high specificity. In addition, ithas no influence by other components in samples. GIP standard is highly purified synthetic product.Specificity:This ELISA kit has high specificity to human GIP(1-42) and GIP(3-42), and shows no cross reactivity toGlucagon, GLP-1(7-37), GLP-1(7-36) NH2, GLP-1(9-36) NH2and human GLP-2.Assay principle:This ELISA kit for determination of human total GIP is based on a sandwich enzyme immunoassay. Tothe wells of plate coated with highly purified mouse monoclonal antibody against human GIP, standardsorsamples are added for the 1st step immunoreaction. After the 1st step incubation and plate washing,HRP labeled antibody solution against human GIP is added as the 2nd step to form antibody - antigen -labeled antibody complex on the surface ofthe wells. After the 2nd step incubation and rinsing outexcess labeled antibody, Finally, HRP enzyme activity is determined by 3,3’,5,5’-Tetramethylbenzidine(TMB) and the concentration of human total GIP is calculated.