Longer-lasting gut insulin signal (GIP Pro3 analog)
A lab-made version of the gut hormone GIP, tweaked to survive longer in the bloodstream so it can stimulate insulin release for longer; used only as a lab research tool.
A researcher, an agent, or an algorithm wrote down the sequence and picked a target to hit.
An AI model like OpenFold3 or AlphaFold built a 3D structure and scored how well it fits the binding site.
A second contributor repeated the computation on their own hardware and the scores matched.
Named peptide fragment — synthesized for research; ClinicalTrials.gov trials registered for parent compound or class
Fork this card to add platform evidence →
Endogenous peptide fragment — receptor binding/activity established in published literature; CT.gov evidence
Fork this card to add platform evidence →
What this is
GIP(Pro3) — also written (Pro3)GIP — is a synthetic analog of GIP (glucose-dependent insulinotropic polypeptide), a gut-derived incretin hormone that stimulates insulin release after meals. It was engineered to resist breakdown by the enzyme DPP-4, which normally inactivates native GIP within roughly 7 minutes in the circulation. The single structural change is a proline substitution at position 3 of the mature GIP sequence — where native GIP carries glutamic acid, (Pro3)GIP carries proline — and that one swap is enough to block the primary DPP-4 cleavage site entirely. The stored 42-residue sequence (beginning Y-A-P-G-T-F…) reflects this substitution: position 3 is proline. Researchers have used (Pro3)GIP primarily as a pharmacological tool to dissect GIPR signalling in rodent models, though a key 2016 study showed its pharmacology at the human receptor is fundamentally different from what rodent work had implied.
History
GIP was first purified from porcine intestinal extracts in 1969 by John Brown and colleagues, initially named "gastric inhibitory polypeptide"; its more consequential function as the first identified incretin hormone — stimulating glucose-dependent insulin secretion from pancreatic beta cells — was established in subsequent years. GIP and GLP-1 together are responsible for the majority of the incretin effect in healthy humans (reviewed by Drucker and colleagues, Annual Review of Physiology, 2014). GIP is secreted by K cells in the upper small intestine and circulates as the biologically active 42-residue form until DPP-4 cleaves the Ala2–Glu3 bond to generate the inactive GIP(3-42) metabolite.
(Pro3)GIP was first characterised in 2002 by Victor Gault and Peter Flatt's group at Ulster University. Their design principle was straightforward: substituting proline at the DPP-4 scissile position should simultaneously protect the peptide from rapid degradation and — by disrupting the N-terminal binding geometry — render it a GIPR antagonist. In rodent experiments the compound appeared to fulfil both goals, and it rapidly became the most widely used chemical tool for probing GIP receptor function in mice and rats. A PEGylated derivative, (Pro3)GIP[mPEG], was later developed to extend the dosing interval in animal studies.
What it does
In rodent models, (Pro3)GIP behaves as a GIPR antagonist and has been used to interrogate what happens metabolically when GIP signalling is suppressed. Chronic daily treatment in diet-induced obese mice reversed body-weight gain, restored plasma glucose and glycated haemoglobin toward normal, improved glucose tolerance and insulin sensitivity, and reduced circulating triglycerides and cholesterol (American Journal of Physiology-Endocrinology and Metabolism, 2008). In genetically obese ob/ob mice, early administration over 60 days prevented the development of diabetes and related metabolic abnormalities (Diabetologia, 2007). These findings supported the idea that blocking GIPR could be a therapeutic approach to obesity-related metabolic disease — a concept that has subsequently evolved in complex ways with the clinical success of the dual GIPR/GLP-1R agonist tirzepatide.
The pharmacological picture changed substantially with the 2016 study by Sparre-Ulrich and colleagues (British Journal of Pharmacology). Using transfected cells expressing human, rat, or mouse GIPR in cAMP accumulation assays, they showed that human (Pro3)GIP is a near-full agonist at the human GIP receptor — with an Emax of approximately 90% relative to native human GIP and an EC50 of 4.7 nM — not a competitive antagonist. At rat and mouse GIPRs, (Pro3)GIP is a partial agonist (Emax ~64% and ~59%, respectively) with competitive antagonist activity (Ki 13 nM at the rat receptor; 61 nM at the mouse receptor). These findings mean that rodent studies using (Pro3)GIP to "block" the GIPR were actually measuring a mixture of partial agonism and antagonism — and that this pharmacology does not translate to the human receptor.
Evidence
- Human: No clinical trials involving (Pro3)GIP have been registered or published. It is a research tool, not a clinical candidate.
- Animal: Extensively used in rodent models as an apparent GIPR antagonist. Preclinical studies demonstrated metabolic benefits in diet-induced and genetically obese mice (improved glucose tolerance, reduced body weight, normalised lipid profile). The Sparre-Ulrich 2016 finding of partial agonism at rodent GIPRs requires that earlier murine results be interpreted cautiously.
- In vitro: Sparre-Ulrich and colleagues (British Journal of Pharmacology, 2016) characterised (Pro3)GIP pharmacology at human, rat, and mouse GIPRs using cAMP accumulation and competition binding assays with ¹²⁵I-human GIP. Full agonism at the human receptor (EC50 4.7 nM, Emax ~90%) and partial agonism with competitive antagonism at rodent receptors (Ki 13 nM rat, 61 nM mouse) were the central findings. The GIP system in the context of obesity and type 2 diabetes research is reviewed in Müller and colleagues (Molecular Metabolism, 2025) and Bailey and colleagues (Peptides, 2024).
Mechanism
(Pro3)GIP binds GIPR, a class B G protein-coupled receptor that couples to Gαs to drive cAMP production in pancreatic beta cells, adipocytes, and other tissues. The Glu3→Pro substitution removes the DPP-4 cleavage site at the Ala2–Glu3 bond, conferring full resistance to this primary inactivation route. At the human GIPR, (Pro3)GIP activates the receptor with near-native efficacy through this same cAMP-PKA pathway. At rodent GIPRs, the identical molecule elicits only partial receptor activation while simultaneously competing with native GIP for binding — a dual partial-agonist/competitive-antagonist profile. Sparre-Ulrich and colleagues attributed the species divergence to differences in the GIP receptor's ligand-binding pocket between humans and rodents, and concluded that "human (Pro3)GIP is not an antagonist at human GIP receptors," advising caution in extrapolating rodent pharmacology data (Sparre-Ulrich et al., 2016).
Open questions
- What is the precise structural basis for the species-specific pharmacological divergence at rodent versus human GIPR?
- Does (Pro3)GIP's full agonism at the human GIPR affect its utility as a dissection tool in human cell or tissue experiments?
- No head-to-head comparison of (Pro3)GIP with selective GIPR antagonist antibodies has been published for human receptor assays.
- Proteolytic stability outside the DPP-4 pathway (e.g., neutral endopeptidases) has not been fully characterised.
Related peptides
- GIP (1–42) human — the endogenous 42-residue incretin hormone from which (Pro3)GIP is derived; released from duodenal K cells after eating.
- Tirzepatide — dual GIP/GLP-1R agonist approved for type 2 diabetes and obesity; the same GIPR pathway that (Pro3)GIP has been used to study in rodents.
Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.
Could a DPP-4-resistant peptide that still activates the human GIP receptor inform next-generation dual-action drug design?
Published data show (Pro3)GIP activates the human receptor near-fully and resists rapid breakdown, so it is a reasonable scaffold to study for the GIPR side of combination therapies, without claiming it matches any approved drug.
Could a longer-lasting GIP receptor agonist help strengthen bone, given GIP's documented actions on bone cells?
GIP is already known to act on bone-forming and bone-resorbing cells through its receptor, so a DPP-4-resistant agonist is a plausible candidate to explore for bone loss, pending direct testing.
What makes this one amino-acid swap produce near-full activation at the human receptor but only partial activation at the rodent one?
Pinning down the structural basis would tell researchers when rodent results for this compound can, and cannot, be trusted for human work.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.7040446400642395 | openfold3-mlx |
| ranking score | 0.7799080610275269 | openfold3-mlx |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.745 | global PDE — lower = better |
| disorder | 0.148 | fraction disordered |
| chain pair ipTM (A, B) | 0.704 | interface quality |
▸3-letter notation
▸recipeopenfold3-mlx 0.3.1
| parameter | value |
|---|---|
| model | openfold3-mlx 0.3.1 |
| weights | aedd8f3eb814e392… |
| hardware | apple_m4_base_16gb |
| mlx version | 0.31.1 |
| python | 3.14.3 |
| random seed | 42 |
| msa strategy | colabfold |
| diffusion samples | 1 |
| runtime | 453s |
| predicted by | mlx@peptide |
| predicted at | 2026-04-22 |
python3 openfold3/run_openfold.py predict --query_json {query.json} --runner_yaml examples/example_runner_yamls/mlx_runner.yml --output_dir {output_dir} --num_diffusion_samples 1 ▸citationbibtex
@peptide{pep10772,
sequence = {YAPGTFISDYSIAMDKIHQQDFVNWLLAQKGKKNDWKHNITQ},
target = {gipr},
author = {peptidemodel},
year = {2026},
status = {bioassayed}
}