Current status on chromogranin A and pancreastatin

The authors review the biochemical and biological properties of chromogranins and pancreastatin. Chromogranins A, B and C are acidic proteins of a molecular mass of 48,000, 76,000 and 67,000, respectively, located in the secretory granules of the neuroendocrine cells. Since large amounts of chromogranin A were found in most neuroendocrine tumours, chromogranin A plasma determination is a diagnostic tool even in silent tumours. Pancreastatin is a peptide derived from chromogranin A, which inhibits insulin secretion, exocrine pancreatic secretion and gastric acid secretion, and which stimulates glucagon secretion. Pancreastatin has different molecular forms, the major form being a high molecular form of 92 amino acids, found by the authors in human stomach- and colon extracts and in a liver metastasis of a gastrinoma. The controlled proteolysis of chromogranin A in gut neuroendocrine cells generates predominantly the high molecular weight form.