Beta-MSH (pig form): brain peptide that curbs appetite and regulates body weight
A natural brain hormone that tells the body to eat less and maintain healthy weight; the pig version is used as a lab research tool to study obesity and appetite disorders.
- Class
- Endogenous melanocortin peptide (porcine)
- Status
- Research / literature-extracted sequence; no approved therapeutic status identified in source file
- Best-supported effect
- Sequence identity established from porcine POMC mRNA cDNA (1983); no functional bioactivity data attached
- Main caveat
- No animal efficacy, in vitro assay, or human data are present in this card's source file; porcine sequence is not the human β-MSH sequence
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 a short peptide hormone released in the brain to help regulate appetite and body weight. It is produced by processing a large precursor protein called POMC (pro-opiomelanocortin), which gives rise to a family of related signals — ACTH, α-MSH, β-MSH, and the endorphins — all from a single gene. This card covers the porcine (pig) form of β-MSH, an 18-residue peptide (DEGPYKMEHFRWGSPPKD) derived from the corresponding segment of porcine β-lipotropin. The porcine sequence differs from certain primate forms at residue 6, where porcine β-MSH carries lysine rather than arginine — an important point for researchers comparing cross-species pharmacology. Because rodents cannot produce β-MSH at all (they lack the required cleavage site in POMC), the porcine form has been a key research tool for studying the biology of this peptide.
History
The existence of a melanocyte-stimulating factor distinct from α-MSH was established in the mid-1950s when researchers isolated a second, larger melanotropic peptide from hog pituitary glands. Harris and Roos published a complete structure determination of porcine β-MSH in the Biochemical Journal in 1959, establishing the 18-residue sequence and identifying the shared His-Phe-Arg-Trp (HFRW) core that all melanocortin peptides rely on for receptor binding. The broader picture fell into place in 1979 when the POMC gene was cloned, revealing that β-MSH, α-MSH, ACTH, and β-endorphin all arise from the same precursor. The complete porcine POMC mRNA sequence, which placed β-MSH within the β-lipotropin segment (residues 41–58), was reported by Boileau and colleagues in 1983 (Nucleic Acids Research). For much of the following decade, research on β-MSH was overshadowed by work on α-MSH and ACTH — partly because the commonly used rat and mouse models do not process POMC into β-MSH. The receptor landscape changed significantly in 1994 when Mountjoy and colleagues mapped the melanocortin-4 receptor (MC4R) to hypothalamic and autonomic circuits governing energy balance, establishing MC4R as the central node through which melanocortin peptides regulate feeding and body weight (Molecular Endocrinology). Interest in β-MSH as an endogenous MC4R ligand then grew substantially, culminating in human genetic evidence linking β-MSH deficiency to obesity (Lee, Challis and colleagues, Cell Metabolism 2006).
What it does
β-MSH acts primarily as an agonist at the melanocortin-4 receptor (MC4R) in the hypothalamus, where it suppresses appetite and promotes energy expenditure. When POMC neurons in the arcuate nucleus are activated — for instance by the satiety hormone leptin — they release β-MSH (along with α-MSH), which then binds MC4R on neurons in the paraventricular nucleus of the hypothalamus (PVH). This drives a "stop eating" signal and increases resting energy expenditure. The net result is negative energy balance: less food consumed, more calories burned. β-MSH also has modest activity at MC1R (pigmentation), MC3R, and MC5R, but MC4R is its primary functional target in energy homeostasis contexts.
A key feature distinguishing β-MSH from α-MSH is its termini: unlike α-MSH, which undergoes N-terminal acetylation and C-terminal amidation during processing, porcine β-MSH retains free termini — neither the raw sequence's N-terminus nor C-terminus is chemically capped. This affects its proteolytic stability and is relevant when interpreting receptor binding data across species.
Evidence
- Human: Human genetic studies show a missense variant in the β-MSH–encoding region of POMC (Tyr221Cys) impairs MC4R binding and co-segregates with severe early-onset obesity and hyperphagia, establishing that β-MSH contributes to the regulation of human body weight (Lee, Challis and colleagues, Cell Metabolism 2006). Quantitative LC-MS/MS profiling of human hypothalamic tissue confirms that β-MSH is produced in considerable amounts alongside desacetyl α-MSH — substantially more abundant than acetylated α-MSH — and that its loss cannot be fully compensated by other melanocortin peptides (PMC6197775). No human trials of porcine β-MSH itself have been conducted; it is a research peptide, not a clinical drug.
- Animal: Central (intracerebroventricular) administration of β-MSH reduces cumulative food intake in rodent models despite the fact that rodents cannot generate endogenous β-MSH (Pomc null mouse study, PMC2204083). Porcine β-MSH has also served as the lead sequence for developing synthetic MC4R-selective agonists with demonstrated efficacy in diet-induced obese rat models, including one analog reported to reduce food intake by 38% and increase fat utilization by 58% at low doses (Zeng Yan and colleagues, Current Topics in Medicinal Chemistry 2007).
- In vitro: β-MSH binds MC4R with moderate-to-high affinity, with Ki values reported in the nanomolar range at recombinant human MC4R depending on assay methodology (Ericson and colleagues, BBA Molecular Basis of Disease 2017; Mountjoy and colleagues, Molecular Endocrinology 1994). The core His-Phe-Arg-Trp pharmacophore is necessary and sufficient for receptor engagement.
Known effects
- Appetite suppression — Mechanistic and preclinical evidence; not tested in human clinical trials as an isolated compound
- Energy expenditure increase — Demonstrated via MC4R signaling in animal models and inferred from human genetic loss-of-function obesity phenotype
- Pigmentation — Weak MC1R activity; melanotropic effect is less pronounced than α-MSH
- Sexual function — MC4R signaling is also implicated in central regulation of sexual arousal; this pathway is shared with setmelanotide and PT-141 but has not been studied specifically for porcine β-MSH
Regulatory status
Porcine β-MSH has no regulatory approval as a therapeutic agent. It is a research-grade peptide used in pharmacological studies of the melanocortin system. The MC4R pathway it activates is the target of setmelanotide (Imcivree), which received FDA approval in 2020 for treatment of severe obesity caused by genetic deficiencies in POMC, PCSK1, or LEPR — conditions where the natural β-MSH/MC4R signaling chain is broken (Qamar and colleagues, touchREVIEWS in Endocrinology 2024).
- US: Not approved; research peptide only
- EU: Not approved; research peptide only
- WADA: Melanocortin agonists acting on MC4R fall under prohibited substance categories; classification as a research tool vs. performance-enhancing agent depends on context
Mechanism
β-MSH is generated by proprotein convertase–mediated cleavage of β-lipotropin, itself a fragment of the POMC precursor. In humans and other large mammals (including pigs), a dibasic cleavage site flanks the β-MSH sequence within β-LPH, allowing PC1/PC2 enzymes to liberate the 18-residue peptide. Rodents lack this cleavage site and do not produce endogenous β-MSH. The porcine sequence DEGPYKMEHFRWGSPPKD shares its core pharmacophore (HFRW, residues 9–12) with all melanocortin peptides; this tetrapeptide adopts a β-turn conformation that positions the key side chains for binding within the MC4R orthosteric pocket.
MC4R is a class A GPCR expressed on glutamatergic neurons of the paraventricular nucleus of the hypothalamus (PVH), as documented by Mountjoy and colleagues (Molecular Endocrinology 1994) and later work on MC4R-expressing PVH neurons projecting to the lateral parabrachial nucleus. Binding of β-MSH activates Gαs-coupled signaling (cAMP elevation), depolarizing these neurons and driving the downstream suppression of feeding and increase in energy expenditure. Yoon and colleagues (Endocrinology and Metabolism 2015) established that MC4R expression in appetite-regulating brain regions is co-distributed with dopamine D2 receptor expression, suggesting integration with dopaminergic reward circuits.
The endogenous antagonist at MC4R is AgRP (agouti-related peptide), released by orexigenic neurons of the arcuate nucleus during fasting. The β-MSH/AgRP balance at MC4R sets the tone of hypothalamic energy-balance signaling. Anti-inflammatory signaling through α-MSH at MC1R and MC3R — documented by Ichiyama and colleagues (Annals of the New York Academy of Sciences 2000) and Clemson and colleagues (Ocular Immunology and Inflammation 2017) — provides context for the broader immunomodulatory role of the melanocortin family, though those effects are primarily α-MSH mediated rather than β-MSH.
Related peptides
- α-MSH — The 13-residue N-terminally acetylated, C-terminally amidated melanocortin from the ACTH segment of POMC; primary endogenous MC1R and MC4R agonist in most mammalian species including rodents
- Setmelanotide (Imcivree) — Synthetic cyclic octapeptide MC4R agonist approved for genetic obesity caused by disrupted POMC→β-MSH→MC4R signaling; the first approved drug that directly validates the endogenous β-MSH pathway
- PT-141 (bremelanotide) — Cyclic melanocortin analog acting at MC3R/MC4R; FDA-approved for hypoactive sexual desire disorder in premenopausal women; illustrates the breadth of MC4R biology beyond appetite regulation
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 from pigs activate faulty hunger receptors that current drugs cannot reach?
If true, children and adults with certain genetic forms of severe obesity could have a new treatment option that works where existing drugs fail.
Could the difference between pig and human beta-MSH explain why some obesity drugs work better in people than in animal models?
If true, drug developers could design receptor-selective versions of beta-MSH that suppress appetite more effectively with fewer side effects, helping people with genetic obesity disorders.
Could beta-MSH send a different cellular message than alpha-MSH even though both bind the same receptor?
If true, drug makers could copy beta-MSH's signaling pattern to create appetite drugs that avoid tolerance and side effects common with current treatments.
Could the part of beta-MSH before the famous HFRW sequence be doing more than just hanging on?
If true, scientists would know exactly which parts to keep when designing simpler, longer-lasting obesity drugs, saving years of trial and error.
Could removing the end of beta-MSH make it survive longer in the bloodstream without losing its hunger-blocking power?
If true, patients could take obesity medications less often while getting the same benefits, making treatment easier to stick with.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.848584771156311 | boltz-2 |
| ranking score | 0.8104149103164673 | boltz-2 |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.821 | 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{pep10520,
sequence = {DEGPYKMEHFRWGSPPKD},
target = {mc4r},
author = {peptidemodel},
year = {2026},
status = {synthesized}
}