Peptide directoryGut, pancreas & liver

GRPP

The first thirty residues of proglucagon, cut free in the pancreas.

Where it comes from

Made in
Alpha cells of the islets, released with glucagon
Sent out by
With glucagon, when glucose falls
Acts on
  • Pancreatic islets (shown in rat organ experiments)
  • Nothing established in people

What it does

  • Strongly held back glucose-stimulated insulin release from an isolated, perfused rat pancreas, and not through the glucagon or GLP-1 receptor 1
  • Had no effect on glucose output from the liver in the same experiments 1
  • In people nothing is established: it travels in blood after meals as part of glicentin, and whether the free peptide does anything is unknown 2

In medicine

  • None: it is a research analyte, and no clinical assay measures it
  • Antibodies raised against glicentin pick it up as well, so human studies report the two together 2

Beyond the body’s own use

  • Not studied as a treatment in people, and no analogue of it has been taken into a trial
  • The open question is whether the rat finding holds in human islets. If it does, a by-product of making glucagon would also be a brake on insulin, which would matter for how the alpha cell talks to the beta cell beside it 1

Sources

  1. Whiting et al., GRPP inhibits glucose-stimulated insulin secretion from the rat pancreas, Physiological Reports 2015
  2. Holst, Enteroglucagon, Annual Review of Physiology 1997

This card describes what a medicine is for and what the evidence says; it recommends nothing. Talk to your clinician about anything you read here.