Ghrelin hunger hormone: shortened lab fragment (Ghrelin [1-27])
A 27-amino-acid piece of the stomach's hunger hormone ghrelin, used in lab studies to understand how ghrelin activates the brain's hunger receptor; experimental, not yet an approved drug.
- Class
- Endogenous peptide fragment (ghrelin-derived)
- Status
- No approved therapeutic status identified
- Best-supported effect
- GHS-R activation and intracellular calcium increase in GHS-R-expressing cells (in vitro)
- Main caveat
- No animal or human efficacy data identified in this card's source file
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.
Snapshot
Class: Endogenous peptide fragment (ghrelin-derived)
Evidence tier: In vitro / assay evidence
Status: No approved therapeutic status identified
Best-supported effect: GHS-R activation and intracellular calcium increase in GHS-R-expressing cells (in vitro)
Main caveat: No animal or human efficacy data identified
What this is
Ghrelin [1-27] is a 27-amino acid fragment of human ghrelin, an endogenous peptide hormone produced primarily in the stomach. The full-length ghrelin peptide contains 28 residues; the [1-27] form lacks the C-terminal arginine (Arg-28) found in full-length ghrelin. Ghrelin [1-27] was identified during biochemical characterization of ghrelin-derived molecules produced by post-translational processing of the ghrelin precursor.
In cell-based assays, synthetic Ghrelin [1-27] has been shown to activate the growth hormone secretagogue receptor (GHS-R) and induce intracellular calcium increases in GHS-R-expressing cells, a response qualitatively similar to that of full-length ghrelin, decanoyl ghrelin, and decanoyl ghrelin [1-27].
Evidence map
| Evidence layer | Grade | What it supports |
|---|---|---|
| Human | None identified | No human trial or observational data identifieds available literature |
| Animal | None identified | No animal study data identifieds available literature |
| In vitro | Weak | GHS-R activation and intracellular calcium increase in GHS-R-expressing cells; from a single structural characterization study |
| Computational | None identified | No structure prediction or docking data identifieds available literature |
| Mechanism | Plausible | GHS-R agonism consistent with parent molecule biology; calcium signaling pathway inferred from receptor class |
Claim check
| Claim | Verdict | Evidence layer | Confidence |
|---|---|---|---|
| Activates GHS-R and induces intracellular calcium increase | Supported (in vitro) | In vitro | Low — single structural characterization study; no independent replication identified in source |
| Equivalent biological activity to full-length ghrelin | Weak (in vitro, partial) | In vitro | Low — qualitative similarity reported in GHS-R calcium assay; functional equivalence across all ghrelin endpoints not established |
| Human efficacy for any indication | Not established | None | Low — no human data present |
Assay conditions
This section reports conditions used in assays. It does not establish animal or human exposure.
| Context | System | Assay condition | Timepoint | Endpoint | Limitation |
|---|---|---|---|---|---|
| In vitro characterization | Cells expressing GHS-R | Synthetic Ghrelin [1-27]; exact concentration not individually extracted from source | Not individually extracted | Intracellular calcium increase | Single study; exact assay concentration, duration, and cell line not individually extracted's available literature |
Assay limitations
- Intracellular calcium response was measured in GHS-R-expressing cell systems; this does not establish in vivo receptor pharmacology, bioavailability, or systemic effect.
- No animal toxicology or human safety data are identifieds available literature.
- Published research characterization study was primarily focused on structural identification of ghrelin-derived molecules, not on pharmacological profiling of Ghrelin [1-27] as an isolated therapeutic candidate.
- In vitro activity in this assay system does not establish systemic tolerability, potency relative to clinical benchmarks, or any human-relevant endpoint.
Mechanism
Ghrelin [1-27] is proposed to act as an agonist at the growth hormone secretagogue receptor (GHS-R), a G protein-coupled receptor expressed in the pituitary and other tissues. GHS-R activation is associated with downstream calcium mobilization via Gq/phospholipase C signaling, which is the basis of the intracellular calcium assay response reported in available literature. This mechanism is inferred from receptor class and parent molecule biology; target specificity relative to full-length ghrelin and potency at GHS-R have not been separately established for Ghrelin [1-27] in the available literature.
Chemistry
| Field | Value |
|---|---|
| Amino-acid chain | GSSFLSPEHQRVQQRKESKKPPAKLQP |
| Full notation | H-Gly-Ser-Ser-Phe-Leu-Ser-Pro-Glu-His-Gln-Arg-Val-Gln-Gln-Arg-Lys-Glu-Ser-Lys-Lys-Pro-Pro-Ala-Lys-Leu-Gln-Pro-OH |
| Length | 27 amino acids |
| Topology | Linear |
| Modification | None reported; unacylated form (lacks the octanoyl modification present in acyl ghrelin) |
| Key difference from parent | Lacks C-terminal Arg-28 of full-length ghrelin |
| Molecular weight | Not individually extracted from available literature |
| CAS | Not individually extracted from available literature |
| Sequence confidence | Verified (matches sequence reported in Hosoda et al. 2003) |
Open questions
- GHS-R potency and selectivity: Relative binding affinity and potency of Ghrelin [1-27] at GHS-R compared with full-length acyl ghrelin and other ghrelin-derived molecules has not been individually characterized in available literature.
- Animal translation: No animal studies using Ghrelin [1-27] as an isolated compound are identifieds available literature. Whether in vitro GHS-R activity translates to in vivo GH release, appetite, or metabolic endpoints is unknown from available literature.
- Human translation: No human data of any kind are identifieds available literature.
- Acylation requirement: Full-length ghrelin requires octanoylation at Ser-3 for high-affinity GHS-R binding; published research does not characterize whether Ghrelin [1-27] (unacylated) retains meaningful GHS-R agonism relative to acyl forms.
- Physiological role: Whether Ghrelin [1-27] is produced endogenously at biologically significant levels and has a distinct physiological function from full-length ghrelin is not addressed in the available literature.
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.
Does this shortened, unacylated ghrelin fragment only partly activate the hunger receptor instead of fully switching it on?
If Ghrelin [1-27] only weakly activates hunger signaling, it could point toward new ways to study or adjust appetite signaling in obesity research.
If you chemically attach a small fat group at Ser3 of this shorter ghrelin piece, does it become as powerful as the natural hormone?
If yes, it could yield a ghrelin analog that is one residue shorter and potentially simpler to make, which is relevant to treatments for muscle wasting and growth hormone deficiency.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.8558362126350403 | boltz-2 |
| ranking score | 0.837988555431366 | boltz-2 |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.547 | global PDE — lower = better |
| disorder | NaN | fraction disordered |
▸3-letter notation
▸recipeboltz-2 1.0
| parameter | value |
|---|---|
| model | boltz-2 1.0 |
| weights | — |
| hardware | nvidia_nim_api |
| mlx version | — |
| python | — |
| random seed | — |
| msa strategy | none |
| diffusion samples | 1 |
| runtime | — |
| predicted by | mlx@peptide |
| predicted at | 2026-04-24 |
▸citationbibtex
@peptide{pep10560,
sequence = {GSSFLSPEHQRVQQRKESKKPPAKLQP},
target = {ghsr},
author = {peptidemodel},
year = {2026},
status = {synthesized}
}