Synthetic fragment peptides of glucose-dependent insulinotropic polypeptide (GIP) were evaluated for their ability to elevate cellular cAMP production and stimulate insulin secretion. In GIP receptor transfected CHL cells, GIP(4–42) and GIP(17–30) dose-dependently inhibited GIP-stimulated cAMP production (40±8%; p<0.01 and 15±6%; p<0.05, respectively), while GIP(1–16) exerted very weak agonist effects on cAMP production. In the clonal pancreatic β-cell line, BRIN-BD11, GIP(1–16) demonstrated weak insulin releasing activity compared with native GIP. In contrast, GIP(4–42) and GIP (17–30) weakly antagonized the insulin releasing activity of the native peptide (23±6%; p<0.05 and 11±3%, respectively). These data demonstrate the critical role of the N-terminus and the involvement of regions of the C-terminal domain in generating full biological potency of GIP.
Cyclic AMP Production and Insulin Releasing Activity of Synthetic Fragment Peptides of Glucose-Dependent Insulinotropic Polypeptide
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V.A. Gault, P. Harriott, P.R. Flatt, F.P.M. O'Harte; Cyclic AMP Production and Insulin Releasing Activity of Synthetic Fragment Peptides of Glucose-Dependent Insulinotropic Polypeptide. Biosci Rep 1 December 2002; 22 (5-6): 523–528. doi: https://doi.org/10.1023/A:1022073819618
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