Volume 140, Issue 5, Pages 1380-1383 (May 2011) Zollinger–Ellison Syndrome: Still a Diagnostic Challenge in the 21st Century?  D. Mark Pritchard  Gastroenterology  Volume 140, Issue 5, Pages 1380-1383 (May 2011) DOI: 10.1053/j.gastro.2011.03.026 Copyright © 2011 AGA Institute Terms and Conditions

Figure 1 Pathways of progastrin processing indicating the cellular organelles involved. Progastrin may be constitutively secreted (colon cancer cells) or converted to 17 and 34 amino acid amidated peptides that are stored in, and released by, secretory vesicles of the regulated pathway (antral and duodenal G cells). Other processing steps (phosphorylation, sulfation) and the optimum pH for cleavage are indicated. Arrows with continuous lines indicate the predominant pathways, whereas dotted lines indicate minor pathways in each cell type. In gastrinoma cells, a variety of amidated and incompletely processed forms of gastrin are secreted, the relative amounts varying between individual tumours. ER, endoplasmic reticulum; TGN, trans-Golgi network; G-gly, glycine-extended gastrin; G-GlyOH, gastrin with C-terminal hydroxy-glycine. Gastroenterology 2011 140, 1380-1383DOI: (10.1053/j.gastro.2011.03.026) Copyright © 2011 AGA Institute Terms and Conditions