PROSITE documentation PDOC00231

Calcitonin / CGRP / IAPP family signature

Calcitonin [1] is a 32 amino acid polypeptide hormone that causes a rapid but short-lived drop in the level of calcium and phosphate in the blood, by promoting the incorporation of these ions in the bones. Alternative splicing of the gene coding for calcitonin produces a distantly related peptide of 37 amino acids, called calcitonin gene-related peptide (CGRP). CGRP induces vasodilatation in a variety of vessels, including the coronary, cerebral and systemic vasculature. Its abundance in the CNS also points toward a neurotransmitter or neuromodulator role.

Islet amyloid polypeptide (IAPP) [2] (also known as diabetes-associated peptide (DAP), or amylin) is a peptide of 37 amino acids that selectively inhibits insulin-stimulated glucose utilization and glycogen deposition in muscle, while not affecting adipocyte glucose metabolism. Structurally, IAPP is closely related to CGRP.

Two conserved cysteines in the N-terminal of these peptides are known to be involved in a disulfide bond. The C-terminal residue of all three peptides is amidated.

                 ****************
                xCxxxxxCxxxxxxxxxxxxxxxxxxxxxxxxxxxx-NH(2)
                 |     |                             Amide group
                 +-----+

'C': conserved cysteine involved in a disulfide bond.
'*': position of the pattern.

The pattern we developed for this family of peptides includes the region of the disulfide bond.