Brain-signaling hormone fragment (γ2-MSH)
A natural peptide made by the body from a brain hormone precursor; activates receptors that help regulate appetite and energy balance; used only as a lab research tool.
- Class
- Endogenous pituitary peptide fragment
- Status
- No approved therapeutic status identified
- Best-supported effect
- Origin and sequence characterized in bovine pituitary tissue; no functional bioactivity data attached to this card
- Main caveat
- No animal efficacy, in vitro assay, or human evidence is attached to 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.
What this is
γ2-MSH (gamma-2 melanocyte-stimulating hormone) is a naturally occurring 12-amino-acid peptide fragment derived from the large precursor protein POMC (proopiomelanocortin), the same gene product that gives rise to ACTH, α-MSH, and β-MSH. It sits at the N-terminal end of POMC, within a region called the pro-γ-MSH domain, and is released when the prohormone convertase PC2 cleaves the larger γ3-MSH fragment down to its 12-residue core. γ2-MSH belongs to the melanocortin peptide family and is primarily recognized as an endogenous ligand at the melanocortin-3 receptor (MC3R), though it binds the melanocortin-4 receptor (MC4R) at much lower potency. Because MC4R is a central regulator of energy balance — and the target of the approved drug setmelanotide — γ2-MSH and its structural relatives have been used as pharmacological probes to map receptor selectivity and inform drug design for obesity (Ericson and colleagues 2017; Yeo and colleagues 2021).
History
The discovery of γ2-MSH traces directly to the 1979 cloning of the POMC cDNA. Nakanishi and colleagues (Nature, 1979) sequenced the bovine POMC gene and showed that the N-terminal domain encoded not one but three MSH-like peptides — γ1-MSH, γ2-MSH, and γ3-MSH — each containing the conserved His-Phe-Arg-Trp pharmacophore found in all melanocortins. γ2-MSH, a 12-residue peptide (YVMGHFRWDRFG), is generated from γ3-MSH by further proteolytic processing and lacks the C-terminal glycosylation that marks the parent fragment. For the following two decades γ-MSH peptides were explored primarily as cardiovascular and renal modulators, since intravenous γ-MSH promotes natriuresis in mice through MC3R-dependent signaling. The cloning of MC3R and MC4R in the early 1990s — and the subsequent discovery by Mountjoy and colleagues (Molecular Endocrinology, 1994) that MC4R is densely expressed in hypothalamic and autonomic circuits — refocused the field on energy homeostasis. γ2-MSH then gained importance as a reference ligand for characterizing receptor selectivity, particularly the pharmacological difference between MC3R and MC4R (Cai and colleagues 2016).
What it does
γ2-MSH acts as an agonist at melanocortin receptors, producing its effects by engaging the conserved HFRW (His-Phe-Arg-Trp) binding pocket that all endogenous melanocortins share. At human receptors, γ2-MSH is strongly preferred at MC3R and shows more than 50-fold lower potency at MC4R, making it one of the more selective endogenous probes for the MC3R subtype. This selectivity reverses somewhat in rodent systems — at mouse receptors, γ2-MSH is roughly equipotent at MC3R and MC5R and only modestly selective over MC4R — a species difference that researchers have found important to account for when interpreting mouse physiology studies (Joseph and colleagues, Peptides, 2010). Through MC3R, γ-MSH peptides participate in sodium homeostasis and blood pressure regulation; through partial activity at MC4R, γ2-MSH can influence energy expenditure pathways, though it is not a potent driver of appetite suppression at physiological concentrations. Because MC4R is the dominant melanocortin receptor for body weight regulation, γ2-MSH's low MC4R potency means it contributes less to satiety signaling than α-MSH or ACTH-derived melanocortins (Yeo and colleagues 2021).
Evidence
- Human: No human trials have been conducted with γ2-MSH itself. Its relevance to human physiology is understood through the broader melanocortin/POMC literature and through trials of derived MC4R agonists: the RM-493 (setmelanotide precursor) study by Chen and colleagues (JCEM, 2015) showed that direct MC4R agonism increases resting energy expenditure in obese humans, contextualizing what γ2-MSH's partial MC4R activity could in principle engage.
- Animal: In MC3R-knockout mouse models, γ-MSH-mediated natriuresis is absent, confirming the MC3R dependence of its renal effects. In vivo potency profiling by Joseph and colleagues (Peptides, 2010) established the species-specific receptor selectivity described above using mouse cell lines stably expressing individual melanocortin receptor subtypes.
- In vitro: Functional EC50 values for γ2-MSH at mouse melanocortin receptors are approximately 38 nM at mMC3R, 420 nM at mMC4R, and 42 nM at mMC5R (Joseph and colleagues 2010). At human receptors, binding Ki values are in the range of 17–57 nM at hMC3R and exceed 6,000 nM at hMC4R, reflecting the pronounced human receptor selectivity for MC3R over MC4R (compiled in Ericson and colleagues 2017).
Known effects
- MC3R agonism — Primary endogenous activity; mediates natriuretic effects in kidney and acts as an inhibitory autoreceptor on hypothalamic POMC neurons (Preclinical, mechanism established)
- Partial MC4R agonism — Low-potency activity at MC4R contributes to energy expenditure pathways in principle, but γ2-MSH is not a potent or selective MC4R agonist (In vitro; EC50 ~420 nM at mouse MC4R)
- MC5R activity in rodents — Equipotent with MC3R at mouse MC5R; this cross-reactivity must be controlled for in rodent studies (In vitro, cautionary finding)
Safety signals
γ2-MSH is an endogenous peptide and has not been tested in human clinical trials. No published safety data exist for exogenously administered γ2-MSH in humans. Early rodent studies of γ-MSH peptides administered intravenously noted acute increases in blood pressure and heart rate in some models (reviewed in Prindle and colleagues 2026), effects attributed to central sympathetic stimulation rather than to MC3R or MC4R agonism specifically. These cardiovascular observations contributed to reduced pharmaceutical interest in this peptide series as a drug scaffold.
Regulatory status
- US: Not approved by the FDA. γ2-MSH is an endogenous peptide with no IND or NDA filing. It is used exclusively as a research tool.
- Research context: γ2-MSH serves as a reference comparator in MC3R/MC4R binding and selectivity studies. The approved MC4R agonist setmelanotide (Imcivree, FDA 2020) was developed through a parallel drug-discovery path that specifically sought to increase MC4R selectivity over the MC3R profile of γ-MSH family peptides (Qamar and colleagues 2024).
- WADA: Not listed as a prohibited substance; no known performance-enhancing use.
Mechanism
MC4R is a class A (rhodopsin-family) G protein-coupled receptor expressed at high density in the paraventricular nucleus and other hypothalamic and autonomic circuits (Mountjoy and colleagues 1994). Upon agonist binding, MC4R couples primarily to Gαs, stimulating adenylyl cyclase and raising intracellular cAMP. Yu and colleagues (Science, 2020) determined the cryo-EM structure of MC4R and identified Ca²⁺ as a cofactor required for ligand binding, resolving the orthosteric pocket where the HFRW pharmacophore docks. γ2-MSH contains this same HFRW motif at positions 5–8 of its sequence (YVMGHFRWDRFG). However, alanine-scanning studies have shown that in γ2-MSH, the Met residue at position 3 is also critical for receptor activation — in contrast to α-MSH analogs where HFRW alone is sufficient — suggesting that the N-terminal residues of γ2-MSH modulate its receptor engagement mode (reviewed in Ericson and colleagues 2017). The structural basis for γ2-MSH's marked selectivity for MC3R over MC4R at human receptors is partly attributed to divergent transmembrane domain 6 sequences between the two receptors; substitution of TM6 residues between MC1R and MC4R significantly modulates γ-MSH analog binding affinity and potency, pointing to this helix as a key determinant of subtype selectivity. Because MC4R enteroendocrine expression also regulates GLP-1 and peptide-YY release (Panaro and colleagues, Cell Metabolism, 2014), MC4R-selective agonists developed from γ-MSH lineage may have effects beyond hypothalamic appetite circuits.
Related peptides
- γ1-MSH — The 11-residue sibling of γ2-MSH, also derived from the POMC N-terminal domain; one residue shorter (lacks the C-terminal Gly) and similarly MC3R-preferring
- α-MSH — The primary endogenous MC4R agonist derived from the ACTH domain of POMC; far more potent at MC4R than γ2-MSH, and the structural template for most clinical melanocortin drugs
- Setmelanotide — FDA-approved cyclic MC4R agonist (Imcivree) designed for genetic obesity; developed through a drug-discovery path that specifically sought to improve on the MC3R-preferred selectivity profile of endogenous γ-MSH peptides (Qamar and colleagues 2024)
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 this brain hormone fragment also quiet pain signals in the spine through the MC4R receptor?
If the pain connection holds, γ2-MSH analogs could inspire a new class of non-opioid pain relievers built from a molecule the body already produces safely.
Could adding a fatty-acid tail to the non-critical end of γ2-MSH make it last long enough in the bloodstream to be a once-weekly obesity treatment?
A longer-lasting version would need far fewer injections than current obesity peptides, improving patient adherence and quality of life.
Could γ2-MSH bind the main hunger-regulating receptor in the brain tightly enough to matter for appetite control?
If true, γ2-MSH would join setmelanotide as a natural reference point for designing obesity drugs, potentially offering a starting scaffold that the body already makes and tolerates.
Does the one extra building block at the end of γ2-MSH make it prefer the MC4R hunger receptor over the related MC3R?
Understanding this switch could guide the design of far more targeted appetite drugs, where hitting the right receptor matters for both efficacy and avoiding side effects.
Does an internal attraction between two charged amino acids in γ2-MSH pre-fold the peptide into the shape needed to activate the hunger receptor?
If this natural clasp exists, drug designers could copy it to make more potent obesity medicines without expensive chemical cyclization steps.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.9166591763496399 | boltz-2 |
| ranking score | 0.8189331293106079 | boltz-2 |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.739 | 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{pep10721,
sequence = {YVMGHFRWDRFG},
target = {mc4r},
author = {peptidemodel},
year = {2026},
status = {synthesized}
}