About Glucagon-Like Peptides
Proglucagon contains, in addition to native glucagon, two glucagon-like peptide sequences GLP-1 and GLP-2, secreted from enteroendocrine cells of the small and large intestine in response to Glucose ingestion.
Once generated, GLP-1 (1-36) is further processed into amidated GLP-1 (7-36) and -in small amounts- glycine-extended GLP-1 (7-37) prior to secretion into the circulation.
GLP-1 (7-36) and (7-37)
Both GLP-1 (7-36) and GLP-1 (7-37), cause glucose-dependent release of insulin by pancreatic beta-cells. They also play a role in gastric motility (gastric emptying), on the suppression of plasma glucagon levels (glucose production) and possibly on the promotion of satiety and stimulation of glucose disposal in peripheral tissues independent from the actions of insulin.
GLP-1 peptides such as GLP-1 (1-36) have been used to investigate restoration of pancreatic beta cell function.
GLP-1 (7-36) has a short half-life, and like GIP, is rapidly degraded by the enzyme dipeptidyl peptidase IV (DPPIV), which is widely expressed. DPPIV cleaves GLP-1 (7-36) into the non or weak-insulinotropic GLP-1 (9-36).
The synthetic GLP-1 like Exendin-4 has a significantly longer half-life, and shows better benefits in the treatment of diabetes.