GIP gut-hormone fragment: research tool (GIP 3-42)
A naturally occurring fragment of GIP, a gut hormone released after eating that helps regulate insulin and metabolism; used only as a lab research tool to study the GIP receptor.
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
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Endogenous peptide fragment — receptor binding/activity established in published literature; CT.gov evidence
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What this is
GIP (3-42) is a naturally occurring fragment of gastric inhibitory polypeptide (GIP), a gut hormone released after eating that helps regulate insulin secretion and metabolism. The full-length GIP hormone is 42 amino acids long; GIP (3-42) corresponds to positions 3 through 42, lacking the first two residues (tyrosine and alanine) present in intact GIP. The stored 40-residue sequence (EGTFISDYSIAMDKIHQQDFVNWLLAQKGKKNDWKHNITQ) begins at the glutamic acid that opens position 3 of the parent hormone. This truncated fragment retains the ability to bind the GIP receptor (GIPR) and is used as a research tool to probe GIP receptor signaling and pharmacology.
History
GIP was first identified in the late 1960s and early 1970s through efforts to isolate acid-inhibitory factors — substances thought to suppress gastric acid secretion after a meal. These candidate substances were historically called "enterogastrones." The work ultimately led to the isolation of GIP as a 42-amino-acid polypeptide (Pederson and colleagues 2016; Marks 2020). Over subsequent decades, the focus of GIP research shifted from gastric acid inhibition toward its role as an incretin — a hormone that amplifies glucose-stimulated insulin secretion from pancreatic beta cells (Seino and colleagues 2010). The N-terminally truncated fragment GIP (3-42) emerged as a pharmacological tool for studying GIPR binding and receptor activity, particularly as interest in the GIP system grew in parallel with the development of dual incretin therapies.
What it does
GIP (3-42) binds to the GIP receptor (GIPR), a class B G-protein-coupled receptor (GPCR) that is widely distributed across peripheral organs and the brain (Usdin and colleagues 1993). In the context of the intact GIP system, GIPR activation in pancreatic beta cells triggers an increase in intracellular cyclic AMP (cAMP), potentiating glucose-stimulated insulin secretion — the classic incretin effect (Seino and colleagues 2010). GIP (3-42) retains GIPR binding activity and is used experimentally to investigate receptor occupancy and competition at the GIPR. Because it lacks the first two residues of full-length GIP, its intrinsic functional activity at the receptor may differ from the intact hormone, though the dossier sources do not report specific binding affinity values for this fragment.
Evidence
- Human: No published clinical data on GIP (3-42) specifically.
- Animal: GIP (3-42) has been studied as a GIPR pharmacology tool; species differences in GIPR ligand behavior are documented in the literature — for example, compounds with altered N-termini show distinct agonist or antagonist profiles depending on whether they are tested at rodent versus human GIP receptors (Sparre-Ulrich and colleagues 2016).
- In vitro: GIPR is a well-characterized class B GPCR; receptor binding and cAMP signaling assays have been used to profile GIP variants and fragments in cell-based systems (Seino and colleagues 2010; Usdin and colleagues 1993).
Mechanism
GIPR belongs to the secretin-vasoactive intestinal peptide receptor family within the class B GPCR superfamily (Usdin and colleagues 1993). Binding of GIP peptides to GIPR activates adenylyl cyclase via Gαs, raising intracellular cAMP in target cells including pancreatic beta cells, adipocytes, and neurons (Seino and colleagues 2010). GIP (3-42) retains the receptor-binding domain of the parent hormone; the significance of the missing N-terminal dipeptide (Tyr-Ala) for signaling efficacy is an active area of pharmacological study. Notably, research on GIPR ligands has revealed meaningful interspecies differences: the truncated or substituted analogs can behave as full agonists at human GIPR while acting as partial agonists or competitive antagonists at rodent GIPR, complicating the translation of murine pharmacology studies to human predictions (Sparre-Ulrich and colleagues 2016).
Known effects
- GIPR binding — Retains binding at the GIP receptor (GIPR); used as a receptor pharmacology research tool
- Incretin pathway engagement — Parent GIP hormone activates cAMP signaling in beta cells, potentiating glucose-stimulated insulin secretion; fragment activity depends on pharmacological context (Seino and colleagues 2010)
- Research context — dual agonist strategy — The GIPR is the target of tirzepatide's GIP agonism arm; GIP (3-42) is used to investigate receptor occupancy and competitive binding in this context (Bailey and colleagues 2024)
Regulatory status
- US: Not approved by the FDA. Research use only.
- EU: Not approved. Research use only.
- WADA: Not listed as a prohibited substance in the current prohibited list.
Related peptides
GIP (3-42) is directly derived from the full 42-amino-acid GIP hormone and is studied within the broader GIP/GLP-1 incretin axis. Related cards on this platform include:
- Full-length GIP (GIP 1-42) — the parent hormone from which this fragment is derived; see also the GIPR target entry.
- Tirzepatide (/card/pep-00018) — a dual GIP/GLP-1 receptor agonist approved for type 2 diabetes and obesity; GIPR agonism is one half of its mechanism, making GIP pharmacology directly relevant to understanding tirzepatide's profile.
- GLP-1 — the other primary incretin hormone; GIP and GLP-1 share incretin function and their receptors are both class B GPCRs (Seino and colleagues 2010).
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.
If we chemically lock the most active helical part of GIP(3-42) into its receptor-binding shape, would it resist breakdown and act for longer?
A version of GIP(3-42) that survives longer in the blood could give researchers a steadier tool to study GIP signaling in animals without constant re-dosing, and could seed new compounds that dial down GIP receptor activity. This is a proposed engineering approach, not yet demonstrated for this fragment.
Does removing the first two amino acids of GIP turn it from a full activator into one that may trigger only part of the receptor's downstream signals, rather than a pure blocker?
GIP(3-42) is usually treated as a clean GIP receptor blocker. If it instead sent partial signals, some experiments that used it to switch off GIP signaling might need re-checking, and it could inform the design of selective GIP receptor drugs for obesity. This is a proposed idea, not an established finding.
If GIP(3-42) occupies the GIP receptor without fully switching it on, could it slow the receptor shutdown that can make some gut-hormone drugs less effective over time?
Some patients on incretin-based obesity drugs see diminishing returns over months. A molecule that helped preserve receptor sensitivity could, in principle, keep these drugs working longer. This is an untested hypothesis that assumes GIP(3-42) acts as a partial blocker.
Beyond blood sugar, could this gut-hormone fragment also affect the bone breakdown that contributes to osteoporosis, since bone cells carry GIP receptors?
If GIP(3-42) influenced bone without triggering the full insulin response, it could point toward separating GIP's bone effects from its metabolic ones, which matters for people with diabetes who face higher fracture risk. This is a speculative repurposing idea that assumes the fragment acts as a partial agonist in bone.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.7024029493331909 | openfold3-mlx |
| ranking score | 0.785611093044281 | openfold3-mlx |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.801 | global PDE — lower = better |
| disorder | 0.170 | fraction disordered |
| chain pair ipTM (A, B) | 0.702 | 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 | 450s |
| 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{pep10531,
sequence = {EGTFISDYSIAMDKIHQQDFVNWLLAQKGKKNDWKHNITQ},
target = {gipr},
author = {peptidemodel},
year = {2026},
status = {bioassayed}
}