Appetite & mood-regulating hormone (β-MSH, monkey version)
A natural hormone fragment found in primates that helps control appetite, body weight, and sexual function by acting on the brain's MC4 receptor; 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.
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
β-Melanocyte-stimulating hormone (β-MSH) is one of the body's natural melanocortin hormones — a short peptide cleaved from a larger protein called pro-opiomelanocortin (POMC), the same precursor that gives rise to α-MSH, γ-MSH, ACTH, and β-endorphin. This particular card is the 18-residue β-MSH sequence (DEGPYRMEHFRWGSPPKD) identified in pig-tailed macaque (Macaca nemestrina), an Old World monkey species whose POMC was an early reference for mapping the primate melanocortin system (Patel and colleagues, DNA 1988). The sequence here is the canonical β-MSH 18-mer fragment as catalogued in evolutionary surveys of the melanocortin family (Dores, Frontiers in Neuroscience 2013). Like α-MSH, it contains the conserved His-Phe-Arg-Trp melanocortin pharmacophore that is responsible for binding the melanocortin receptors. In humans, the corresponding β-MSH peptide is a slightly longer 22-residue form (AEKKDEGPYRMEHFRWGSPPKD); that variant is catalogued separately as β-MSH (human).
History
The story of β-MSH belongs to the broader history of pituitary peptide hormones. After the 1916 description of pituitary "intermedin" activity that darkened amphibian skin, Aaron Lerner's group and parallel teams in the 1950s isolated both α-MSH and β-MSH from pig and bovine pituitary pars intermedia extracts. The relationship between α-MSH, β-MSH, ACTH, and β-endorphin was clarified across the 1970s with the identification of pro-opiomelanocortin (POMC) as the common precursor cleaved by tissue-specific prohormone convertases. The monkey β-MSH sequence catalogued on this card was specifically characterized from a Macaca nemestrina POMC cDNA by Patel and colleagues (DNA 1988), an early primate POMC sequence that contributed to comparative analysis of melanocortin precursor processing across mammals. The modern era of melanocortin pharmacology opened in 1992 when Roger Cone's group cloned the first melanocortin receptors, with MC4R characterized soon after — Mountjoy and colleagues (Molecular Endocrinology 1994) mapped its localization in neuroendocrine and autonomic control circuits of the brain, providing the anatomical basis for understanding why melanocortin signaling controls feeding, energy expenditure, and autonomic tone. The arc from that receptor identification to clinical drugs is reviewed in Ericson and colleagues (Biochimica et Biophysica Acta — Molecular Basis of Disease 2017) and Yeo and colleagues (Molecular Metabolism 2021).
What it does
β-MSH activates the melanocortin receptor family — most relevantly for this card, MC4R, the receptor controlling appetite and energy expenditure in the brain. When β-MSH binds MC4R on neurons in the hypothalamic paraventricular nucleus, it tells the body "you have eaten enough" and turns up energy expenditure, the same satiety circuit that endogenous α-MSH drives. β-MSH also activates the other neural melanocortin receptors (MC3R, MC5R) and MC1R on skin melanocytes, where melanocortin signaling drives pigment production. The reason β-MSH is interesting for research rather than as a drug is the same pharmacokinetic limitation that affects native α-MSH: linear melanocortin peptides are degraded rapidly in circulation, so all the clinically useful melanocortin drugs — setmelanotide, bremelanotide, afamelanotide — are engineered protease-resistant analogs rather than native sequences (Qamar and colleagues, touchREVIEWS in Endocrinology 2024; Ericson and colleagues 2017). The conserved His-Phe-Arg-Trp motif at the core of β-MSH is the structural feature that gave rise to the entire generation of cyclic and lactam-bridged melanocortin analogs that followed (Grieco and colleagues, Journal of Peptide Research 2003).
Mechanism
MC4R is a class A Gαs-coupled G-protein-coupled receptor: melanocortin binding raises intracellular cAMP and engages PKA/CREB signalling, with ERK1/2 as an additional downstream cascade — both pathways are documented in alanine-scanning studies of the receptor's DRYxxI motif and intracellular loop 2 (Yang and colleagues, International Journal of Molecular Sciences 2020). The His-Phe-Arg-Trp core present in α-MSH, β-MSH, and γ-MSH is the minimal pharmacophore that engages this receptor family, and modifying this motif within cyclic peptide scaffolds is the structural basis for the receptor-selective melanocortin analogs developed over the past three decades (Grieco and colleagues 2003). β-MSH carries this conserved motif within an extended N- and C-terminal context (the DEGPY… and …GSPPKD flanking residues) that differs from α-MSH, and these flanking residues contribute to subtype selectivity and affinity profiles distinct from α-MSH. The broader leptin → POMC → α-/β-MSH → MC4R satiety pathway is the central nervous system pathway that loss-of-function mutations disrupt in monogenic obesity syndromes, and is the pharmacological target of MC4R-agonist drug development (Yeo and colleagues 2021).
Evidence
- Human: No clinical trials of native β-MSH itself in humans — this peptide is a research reagent and a comparative-pharmacology reference, not a therapeutic candidate. Clinical proof of concept for MC4R-pathway pharmacology comes from MC4R-selective agonists: setmelanotide (RM-493) has been tested in obese individuals and shown to increase resting energy expenditure (Chen and colleagues, Journal of Clinical Endocrinology & Metabolism 2015) and is now FDA-approved for rare monogenic and acquired hypothalamic obesity (Qamar and colleagues 2024).
- Animal / comparative: The β-MSH sequence catalogued on this card was characterized from Macaca nemestrina POMC by Patel and colleagues (1988); comparative analysis of melanocortin precursors and receptors across vertebrates is reviewed in Dores (Frontiers in Neuroscience 2013).
- In vitro / mechanistic: The structural and signalling pharmacology of the melanocortin receptors β-MSH engages is mapped in detail — receptor mutagenesis studies (Yang and colleagues 2020), structure-activity studies on melanocortin peptide analogs at hMC3R/hMC4R/hMC5R (Grieco and colleagues 2003), and broader reviews of the pathway (Ericson and colleagues 2017; Yeo and colleagues 2021) constitute the bulk of the mechanistic literature.
Known effects
- Appetite suppression and energy-expenditure increase via MC4R — Mechanistic; the central nervous system pathway is well established (Mountjoy and colleagues 1994; Yeo and colleagues 2021). Clinical proof-of-concept in humans is provided by the MC4R-selective agonist setmelanotide (Chen and colleagues 2015).
- Pigmentation signalling via MC1R — Mechanistic; the conserved melanocortin pharmacophore engages MC1R on melanocytes, the canonical pigmentation receptor (Ericson and colleagues 2017).
- Anti-inflammatory and neuroimmunomodulatory activity — Ascribed to the melanocortin family broadly; α-MSH is the best-studied member in this context, with documented modulation of ocular immune privilege (Clemson and colleagues, Ocular Immunology and Inflammation 2017). The extent to which native β-MSH replicates this profile in vivo is less directly characterized than for α-MSH.
Safety signals
There are no human safety data for exogenous native β-MSH because it has not been developed as a therapeutic — it is supplied as a research reagent for cell-culture and preclinical work only. Clinical safety information for the melanocortin pathway therefore derives from the engineered analogs that have undergone human testing. For MC4R agonism specifically, the setmelanotide development program provides the most relevant pharmacovigilance dataset (Chen and colleagues 2015; Qamar and colleagues 2024). On the disease-biology side, loss-of-function mutations in MC4R cause monogenic obesity, and disruption of the upstream leptin → POMC → MC4R circuit is the molecular cause of several rare obesity syndromes that setmelanotide is now approved to treat (Yeo and colleagues 2021).
Regulatory status
- US: Native β-MSH is not an FDA-approved drug and has never been developed as one. It is available as a research reagent for cell-culture and preclinical use only.
- EU/UK: Not approved as a therapeutic in any major international jurisdiction.
- WADA: Not specifically named on the WADA Prohibited List, but any melanocortin-receptor agonist administered exogenously is best treated as falling under S2 (peptide hormones and releasing factors) or S0 (non-approved substances) by mechanism — athletes considering any compound in this family should treat it as potentially prohibited and seek explicit guidance.
- Approved melanocortin drugs (for context, not as β-MSH products): Imcivree (setmelanotide) is the MC4R-selective agonist drug whose pharmacology is closest to this card's mechanism of interest (Qamar and colleagues 2024).
Related peptides
- β-MSH (human) — the 22-residue human β-MSH (AEKKDEGPYRMEHFRWGSPPKD); same C-terminal sequence as this monkey form with four additional N-terminal residues. Same pharmacology, distinct catalogued sequence.
- α-MSH — the 13-residue parent melanocortin hormone (Ac-SYSMEHFRWGKPV-NH₂); shares the His-Phe-Arg-Trp pharmacophore. The native α-MSH peptide has the same pharmacokinetic limitation as β-MSH (rapid degradation) and is itself not used therapeutically.
- Setmelanotide (Imcivree) — the MC4R-selective agonist drug developed off the melanocortin pharmacology that β-MSH exemplifies; FDA-approved for rare monogenic and acquired hypothalamic obesity (Qamar and colleagues 2024).
- Bremelanotide (PT-141, Vyleesi) — a melanocortin-receptor agonist developed within the same chemical program, FDA-approved for premenopausal hypoactive sexual desire disorder.
- γ-MSH — the third POMC-derived melanocortin (KYVMGHFRWDRF-NH₂ in the canonical 12-residue form); shares the His-Phe-Arg-Trp motif but has receptor-preference and tissue-distribution patterns distinct from α- and β-MSH (Dores 2013).
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 the tail end of this hormone reach a second docking point on its receptor, not just the main one?
If true, drug designers could tweak that tail to make medicines that only trigger desired effects, like appetite suppression, while skipping unwanted ones like skin darkening.
Could this hormone send a different internal signal through its receptor than other similar hormones, even though it binds the same target?
If true, it could lead to obesity drugs that suppress appetite without causing heart problems or losing effectiveness over time, because the cellular message would be cleaner.
Could scientists attach this hormone to a brain-entry taxi at its tail end without breaking its appetite-suppressing function?
If true, it could solve a major problem: current appetite drugs cannot reach the brain well. A hormone-shuttle combo could reach the right brain circuits directly, helping people with severe obesity or wasting diseases.
Could this appetite hormone switch off inflammation in brain immune cells, not just control hunger?
If true, it might help people with brain diseases where inflammation damages neurons, such as Parkinson disease, by doing two jobs at once: regulating appetite and protecting brain cells.
Could the shorter monkey form of this appetite hormone be a more precise key for the same brain lock?
If true, drug developers could copy the shorter monkey sequence to make more potent, selective weight-loss drugs with fewer side effects. Patients with obesity could benefit from a cleaner-acting therapy.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.9238689541816711 | boltz-2 |
| ranking score | 0.8502645492553711 | boltz-2 |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.586 | 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{pep10521,
sequence = {DEGPYRMEHFRWGSPPKD},
target = {mc4r},
author = {peptidemodel},
year = {2026},
status = {synthesized}
}