Amylin (revision 4)
Old revision·14:25, 19 Sep 2024·SarcopeniaSefa
| Amylin | |
|---|---|
| Also known as | Islet amyloid polypeptide (IAPP) |
| Source | Pancreatic beta cell, co-secreted with insulin |
| Residues | 37 |
| Compound infobox · conventions | |
Amylin, also called islet amyloid polypeptide (IAPP), is a 37-residue peptide hormone stored in the same secretory granules as insulin and released with it in an approximately 1:20 molar ratio. Its physiological actions are complementary to those of insulin: it slows gastric emptying, suppresses postprandial glucagon secretion, and promotes satiety.[1]
Amylin does not have a dedicated receptor. It acts at the calcitonin receptor in complex with one of three receptor-activity-modifying proteins, RAMP1, RAMP2 or RAMP3, which together constitute the AMY1, AMY2 and AMY3 receptors. The principal site of action for the satiety effect is the area postrema, outside the blood-brain barrier.[1]
Physiology
[edit]Amylin is co-packaged with insulin in the beta-cell secretory granule and released by the same stimuli, so its plasma profile mirrors that of insulin. Fasting concentrations are in the low picomolar range and rise several-fold after a meal.[1]
Its three principal actions all restrain nutrient entry rather than promoting disposal. Gastric emptying slows, which flattens the postprandial glucose excursion. Glucagon secretion is suppressed in the postprandial state — but not during hypoglycaemia, where counter-regulation is preserved. Food intake falls through hindbrain signalling that is distinct from, and additive to, the GLP-1 satiety pathway.