Amylin

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islet amyloid polypeptide
Identifiers
Symbol	IAPP
HUGO	5329
Entrez	3375
OMIM	147940
RefSeq	NM_000415
UniProt	P10997
Other data
Locus	Chr. 12 p12.3-p12.1

Amylin, or Islet Amyloid Polypeptide (IAPP), is a 37-residue peptide hormone secreted by pancreatic β-cells at the same time as insulin (in a roughly 100:1 ratio).

1 Structure
2 Function
3 History
4 Pharmacology
5 References
6 External links

[edit] Structure

The human form of IAPP has the amino acid sequence KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY, with a disulfide bridge between cysteine residues 2 and 7. The peptide is secreted from the pancreas into the blood circulation and eventually excreted by the kidneys. IAPP is capable of forming amyloid fibrils in vitro. Within the fibrillization reaction, the early prefibrillar structures are extremely toxic to insuloma cells cultures. Later amyloid fibril structures also seem to have some cytotoxic effect on cell cultures. Rats and mice have proline residues that prevent the formation of amyloid fibrils.

[edit] Function

Amylin functions as part of the endocrine pancreas and contributes to glycemic control. Although amylin's normal role may not yet be fully known, it aids in limiting glycemic excursions by slowing gastric emptying, promoting satiety, and inhibiting inappropriate secretion of glucagon, a catabolic hormone that opposes the effects of insulin and amylin.

Rodent amylin knockouts are known to fail to achieve the normal anorexia following food consumption. Because it is an amidated peptide, like many neuropeptides, it is believed to be responsible for the anorectic effect.

[edit] History

IAPP was identified independently by two groups as the major component of diabetes-associated islet amyloid deposits in 1987.^[1]^[2]

[edit] Pharmacology

Synthetic amylin, or pramlintide (brand name Symlin) was recently approved for adult use in patients with diabetes mellitus type 1. Insulin and pramlintide, injected separately but both before a meal, work together to control the post-prandial glucose excursion.^[3]