Transit of ProGIP from the ER Lumen to Secretory Granules Processing of preproGIP to proGIP Processing of proGIP to GIP Secretion of Glucose-dependent Insulinotropic Polypeptide from Intestinal K Cells Proteolytic Cleavage of Glucose-dependent Insulinotropic Polypeptide (GIP) PathwayStep2059 PathwayStep2060 PathwayStep2063 PathwayStep2064 PathwayStep2061 PathwayStep2062 Synthesis of prepro-Glucose-dependent Insulinotropic Polypeptide (preproGIP) in Intestinal K Cells Synthesis, Secretion, and Inactivation of Glucose-dependent Insulinotropic Polypeptide (GIP) Authored: May, B, 2009-05-18 21:31:59 Edited: May, B, 2009-09-09 In K cells of the intestine the transcription factors PAX6 and PDX-1 activate transcription of the gene encoding Glucose-dependent Insulinotropic Polypeptide (GIP, first called Gastric Inhibitory Peptide). ProGIP is cleaved in secretory granules by Prohormone Convertase 1 (PC1) at 2 sites to yield mature GIP. In response to fat the GIP is secreted into the bloodstream. The half-life of GIP in the bloodstream is determined by Dipeptidyl Peptidase IV, which cleaves 2 amino acids at the amino terminus of GIP, rendering it biologically inactive. Pubmed17263764 Pubmed17498508 Pubmed19074620 Reactome Database ID Release 43400511 Reactome, http://www.reactome.org ReactomeREACT_23824 Reviewed: Bloom, SR, 2010-06-24