Somatostatin-28 fragment: piece of a natural hormone
A small piece of the body's natural somatostatin-28 hormone; used only as a lab tool to study how hormones connect to their receptors.
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
Somatostatin-28 (1-12), abbreviated SS28(1-12), is a 12-amino-acid peptide naturally produced in the body as one of the two halves of a longer hormone called somatostatin-28. When the body processes somatostatin-28, it can be cleaved into two pieces: the well-known 14-residue somatostatin (the C-terminal half, SS-14) and this lesser-known N-terminal fragment, SS28(1-12). The stored sequence here is SANSNPAMAPRE — the unmodified 12-residue N-terminal segment of pro-somatostatin. It was first characterized in mammalian tissue extracts in the early 1980s as an immunoreactive peptide separate from SS-14 (Benoit 1982).
History
SS28(1-12) was identified in 1982 by Benoit and colleagues, who used an antiserum directed against amino acids 1–11 of somatostatin-28 to look for the predicted N-terminal fragment in rat tissues. They recovered an immunoreactive peptide of approximately 1,250 daltons from acid extracts of both rat hypothalamus and pancreas, and confirmed by reverse-phase HPLC and cation-exchange chromatography that the fragment exists endogenously, not just as an in vitro processing artifact (Benoit 1982, PNAS). Within the next year, Bakhit and colleagues (Nature 1983) showed that SS28(1-12) is actively released from rat hypothalamus in vitro, establishing it as a regulated secretory product rather than a passive degradation fragment. Ravazzola and colleagues (PNAS 1983) then used immunocytochemistry with antisera against both SS-28 and SS28(1-12) to localize the fragment in pancreatic and gastric D cells, observing that anti-SS28(1-12) staining concentrated in mature secretory granules while anti-SS-28 staining was stronger over immature granules — consistent with progressive processing of pro-somatostatin to the (1-12) fragment as granules mature.
What it does
SS28(1-12) is co-stored and co-released with other somatostatin-family peptides from neuroendocrine D cells in the pancreas and gut, and from neurons in the hypothalamus (Benoit 1982; Bakhit 1983; Ravazzola 1983). Its functional role as a signaling peptide in its own right — as opposed to a processing intermediate — has been less thoroughly characterized than that of SS-14 or SS-28. The dossier sources establish where it is found and that it is released in a regulated way, but do not pin down a dedicated receptor or downstream cascade. Later work has continued to detect SS28(1-12) in neuropeptidomic surveys of mammalian brain tissue (Petruzziello 2012), and somatostatin-family peptides more broadly have been discussed as candidate targets for anticonvulsant drug development (Clynen 2014).
Evidence
- Human: No human trials of SS28(1-12) as a discrete agent are present in the dossier.
- Animal: Endogenous presence in rat hypothalamus and pancreas demonstrated by immunoassay and chromatography (Benoit 1982). Active in vitro release from rat hypothalamus shown by Bakhit and colleagues (Nature 1983). Immunocytochemical localization to mature secretory granules of pancreatic and gastrointestinal D cells (Ravazzola 1983).
- In vitro / mass spectrometry: Detected as an endogenous neuropeptide in a comprehensive mass-spectrometric survey of the tree shrew (Tupaia belangeri) neuropeptidome (Petruzziello 2012).
Known effects
- Tissue distribution — present in hypothalamus and pancreas as a discrete, immunologically distinguishable peptide (Benoit 1982).
- Regulated release — actively released from hypothalamic tissue in vitro (Bakhit 1983).
- Co-storage with somatostatin — localized in mature secretory granules of pancreatic and gut D cells alongside SS-28 and its other processing products (Ravazzola 1983).
- Independent signaling role — not established in the dossier; this remains an open question.
Regulatory status
SS28(1-12) is an endogenous peptide fragment used as a research reagent. No approved therapeutic indication and no marketing authorization are documented in the dossier.
Related peptides
- Somatostatin and its C-terminal fragment SS-14 are the better-characterized members of the same pro-somatostatin family; SS28(1-12) is the complementary N-terminal piece released by the same processing step that produces SS-14 from SS-28.
Open questions
- Whether SS28(1-12) acts on a dedicated receptor distinct from the somatostatin receptor family (SSTR1–5) is not established in the dossier.
- The card's structured metadata lists GHSR (ghrelin receptor) as a target, but none of the dossier references demonstrate SS28(1-12) binding at GHSR1a; this annotation needs primary-source confirmation before being treated as established.
- Half-life, clearance route, and stability of SS28(1-12) in circulation are not characterized in the available sources.
- Functional consequences of SS28(1-12) release — separable from those of co-released SS-14 and SS-28 — have not been mapped.
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 the somatostatin-28 fragment SS28(1-12) calm down the ghrelin receptor to reduce appetite and growth hormone signals?
If confirmed, this small natural peptide could become the basis for new treatments targeting hunger and growth hormone excess, offering a second path to appetite control alongside existing ghrelin-blocking approaches and potentially useful in obesity or conditions where overactive ghrelin signalling is a problem.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.8383985757827759 | boltz-2 |
| ranking score | 0.8433460593223572 | boltz-2 |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.703 | 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{pep10642,
sequence = {SANSNPAMAPRE},
target = {ghsr},
author = {peptidemodel},
year = {2026},
status = {synthesized}
}