GIP (1-39): natural gut hormone that triggers insulin release
A shorter natural form of the gut hormone GIP, which tells the pancreas to release insulin after a meal; the same hormone pathway targeted by the diabetes and weight-loss drug tirzepatide. A natural hormone, not an approved drug itself.
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.
A chemistry service or a researcher ordered the sequence, it was manufactured, and mass spectrometry confirmed the right molecule was produced.
A binding or activity measurement confirmed that it actually does what the computer predicted — or didn't.
What this is
GIP (1-39) is a 39-amino-acid form of the gut hormone GIP (glucose-dependent insulinotropic polypeptide, also called gastric inhibitory polypeptide). GIP is one of the two main incretin hormones — gut-released signals that tell the pancreas to put out more insulin after a meal (Seino 2010). The full-length canonical human hormone is 42 amino acids (Pederson 2016); the 1-39 form characterized by Xie and colleagues (2004) is a shorter natural variant with insulin-releasing activity in its own right. GIP matters today because its receptor, GIPR, is the second target hit by tirzepatide and other dual GLP-1R/GIPR agonists now used for type 2 diabetes and obesity.
History
The hormone that became GIP was first identified through decades of work on "enterogastrones" — gut factors that inhibit stomach acid secretion — and was eventually isolated as a 42-amino-acid polypeptide; Pederson (2016) gives a first-person account of the discovery arc, including the early focus on acid inhibition and the later recognition that the peptide's defining role was glucose-dependent stimulation of insulin release. The receptor (GIPR) was cloned from human tissue by Yamada and colleagues (1995), placing it in the class B (secretin-VIP) family of G-protein-coupled receptors. Usdin and colleagues (1993) mapped GIPR distribution and showed it is expressed widely in peripheral organs and the brain, foreshadowing the non-pancreatic roles (adipose, bone, CNS) that have become central to modern GIP pharmacology. The specific 1-39 form was reported by Xie and colleagues (2004) as a distinct insulinotropic variant of GIP.
What it does
In its core physiological role, GIP is released from K-cells of the duodenum and upper small intestine after a meal and acts on pancreatic β-cells to amplify glucose-stimulated insulin secretion — the classic incretin effect (Seino 2010, Bailey 2024). It is glucose-dependent: GIP only drives insulin release when blood glucose is elevated, which is why it does not cause hypoglycemia on its own. GIP also acts beyond the pancreas — its receptor is present in adipose tissue, bone, and the central nervous system (Usdin 1993), and GIP signaling has been studied in lipid handling, bone turnover, and neuroprotection (Ji 2016). The interplay between GIP and GLP-1 — both signaling through related class B GPCRs that activate cAMP in β-cells — is the basis of the dual-agonist drug class (Seino 2010).
Mechanism
GIPR is a class B G-protein-coupled receptor that couples primarily to Gαs, raising intracellular cAMP in β-cells and other GIPR-expressing tissues; in pancreatic islets this potentiates glucose-triggered insulin secretion (Seino 2010, Yamada 1995). Truncation of GIP at either terminus changes its pharmacology sharply: Hansen and colleagues (2016) showed that N- and C-terminally shortened forms of the naturally occurring amidated truncation GIP(1-30)NH₂ can become high-affinity competitive antagonists rather than agonists at the human GIP receptor, illustrating how a few residues at the N-terminus determine whether the ligand activates the receptor. Species also matters: Sparre-Ulrich and colleagues (2016) demonstrated that (Pro3)GIP — long used as a "GIP receptor antagonist" in rodent work — is in fact a full agonist at the human GIP receptor while behaving as a partial agonist/competitive antagonist in rats and mice, a caveat that reframes how rodent GIP-antagonism literature translates to humans. The stored sequence here is the 39-residue form; the canonical full-length human hormone is 42 amino acids (Pederson 2016), and the active circulating pool in vivo is a mix of full-length and naturally truncated species.
Evidence
- Human: GIP has been studied in human physiology for decades as one of the two principal incretin hormones; its receptor is the target of approved dual-incretin drugs (tirzepatide) and of investigational GIPR-antagonist conjugates such as AMG 133 (maridebart cafraglutide), which has progressed through phase 1 with weight-loss signals (Véniant 2024).
- Animal: Long-acting protease-resistant GIP analogs have been developed and tested in rodent models for type 2 diabetes and, separately, for neuroprotection in Alzheimer's-related paradigms (Ji 2016). Species-specific pharmacology of GIP analogs has been characterized in rat, mouse, and human receptor systems (Sparre-Ulrich 2016).
- In vitro: GIPR pharmacology — agonism, antagonism, and the consequences of N-/C-terminal truncation — has been mapped in transfected cell systems (Hansen 2016, Sparre-Ulrich 2016, Yamada 1995).
Known effects
- Glucose-dependent insulin secretion — Established physiological role; basis of the incretin concept (Seino 2010).
- Adipose and bone signaling — GIPR is expressed outside the pancreas; GIP has documented roles in lipid handling and bone turnover (Usdin 1993, Bailey 2024).
- Neuroprotection (preclinical) — Long-acting GIP analogs cross the blood-brain barrier and show neuroprotective effects in Alzheimer's-related rodent paradigms (Ji 2016).
- Drug-target validation for obesity/T2D — GIPR is one of the two receptors engaged by tirzepatide and by the bispecific GIPR-antagonist/GLP-1-agonist AMG 133 (Véniant 2024, Bailey 2024).
Regulatory status
GIP (1-39) itself is not an approved drug. The hormone is studied as the endogenous ligand of GIPR; the receptor is the clinical target of approved and investigational therapeutics, not GIP (1-39) as a peptide product.
Related peptides
- GLP-1 — the other major incretin hormone; GIP and GLP-1 together account for the incretin effect on insulin secretion (Seino 2010). GLP-1 is processed from the proglucagon precursor; the related hormone glucagon shares that precursor.
- Semaglutide and liraglutide — GLP-1 receptor agonists that engage only the GLP-1 arm of the incretin system, in contrast to dual GIP/GLP-1 agonists.
- Exenatide — first-in-class GLP-1 receptor agonist; useful contrast to GIP biology.
- Tirzepatide — dual GIP/GLP-1 receptor agonist; engages GIPR as one of its two targets. AMG 133 (maridebart cafraglutide) takes the opposite approach at GIPR — antagonism rather than agonism — while still agonizing GLP-1R (Véniant 2024).
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 hormone your gut already makes naturally activate both of the receptors that today's best diabetes and obesity drugs target?
If true, the body's own GIP hormone might weakly activate the GLP-1 receptor as a side effect of their near-identical shapes, which could mean researchers have a simpler natural starting point for designing dual-action drugs, potentially avoiding the complex chemical modifications used in tirzepatide. This matters for anyone hoping for cheaper or cleaner next-generation metabolic medicines.
Could a hormone released after eating protect brain cells from Alzheimer's-related damage, even in people with perfectly normal blood sugar?
If this holds, GIP(1-39) might reduce the toxic protein tangles and cell death that drive Alzheimer's through a brain pathway that does not depend on glucose at all, meaning it could theoretically help people who do not have diabetes. That would open the door to a simpler, more targeted treatment backbone for a disease that still has very few effective options.
Could there be a way to make a molecule that grabs the GIP receptor tightly but does not switch it on, giving researchers a precise off-switch tool?
If a small stretch near the middle of GIP is what actually flips the receptor into its active state, scientists could design blockers that occupy the receptor without triggering it. Researchers studying GIP's role in metabolism and weight currently lack reliable human-compatible tools to do this, so such a blocker could unlock years of stalled experiments.
Could the natural GIP hormone be modified to stay active in the body for 24 hours or more, the way the drugs semaglutide and tirzepatide do, without breaking what makes it work?
Native GIP disappears from the bloodstream in about 34 minutes, which makes it impractical as a medicine. If the cluster of lysine building blocks at the far end of GIP can be used as attachment points for a fatty acid, the way approved drugs already use this trick, it might be possible to create a long-acting GIP therapy from the simplest possible natural template, potentially at lower manufacturing complexity and cost than current engineered drugs.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.745458722114563 | openfold3-mlx |
| ranking score | 0.8132461905479431 | openfold3-mlx |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.729 | global PDE — lower = better |
| disorder | 0.145 | fraction disordered |
| chain pair ipTM (A, B) | 0.745 | 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 | 447s |
| 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{pep10691,
sequence = {YAEGTFISDYSIAMDKIRQQDFVNWLLAQKGKKSDWKHN},
target = {gipr},
author = {peptidemodel},
year = {2026},
status = {synthesized}
}