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What Is MT-2? Melanotan II Melanocortin Receptor Research Guide for UK Laboratory Research
What is MT-2? MT-2 — formally Melanotan II, a synthetic analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) — is a cyclic heptapeptide engineered from the native alpha-MSH sequence to act as a non-selective agonist across multiple melanocortin receptor subtypes. This page covers MT-2 as a research compound in its own right — its structure, receptor pharmacology, and place within the melanocortin signalling system — as a companion to, not a replacement for, the site’s existing dose-format research guide.
MT-2 is supplied for in-vitro laboratory research only. It is not licensed by the MHRA as a medicinal product, and no dosing or administration guidance is provided in this guide or in any Ascend Peptides UK documentation.
Every batch of MT-2 supplied by Ascend Peptides UK is HPLC verified at ≥98% purity by Janoshik laboratory, LC-MS confirmed for molecular identity, and accompanied by a publicly verifiable Certificate of Analysis.
What Is MT-2 at the Molecular Level?
MT-2 is a synthetic cyclic heptapeptide analogue of alpha-MSH. Its structure was developed from earlier linear alpha-MSH fragment work by cyclising the peptide backbone through a lactam bridge, a modification designed to lock the molecule into a more receptor-favourable conformation and increase resistance to enzymatic degradation compared with linear analogues (Al-Obeidi et al., 1989). The molecular identity is documented below.
|
Molecular Property |
Value |
|---|---|
|
Compound name |
MT-2 / Melanotan II (MT-II); not an INN-assigned compound |
|
Peptide class |
Cyclic alpha-MSH analogue; heptapeptide |
|
Sequence |
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ |
|
Structural modifications vs native alpha-MSH |
Norleucine (Nle) and D-phenylalanine substitutions corresponding to residues 4 and 7 of the native alpha-MSH/NDP-MSH parent sequence — not positions 4 and 7 of the shortened seven-residue MT-2 molecule itself; lactam-bridge cyclisation between the Asp and Lys sidechains |
|
Cyclic structure |
Yes — lactam (amide) bridge between the aspartic acid γ-carboxyl and lysine ε-amino sidechains, closing the peptide into a ring |
|
Molecular formula |
C₅₀H₆₉N₁₅O₉ (PubChem CID 92432) |
|
Molecular weight |
≈1,024.18 g/mol |
|
Receptor activity |
Non-selective melanocortin receptor agonist — MC1R, MC3R, MC4R, MC5R |
|
Supplied format |
Lyophilised powder |
|
Research category |
Melanocortin / Skin & Cellular Research Peptide |
|
Third-party testing |
Janoshik — HPLC + LC-MS verified |
Note on molecular identifiers: published sources are not fully consistent on which PubChem Compound ID (CID) is correctly associated with Melanotan II under this exact name — the formula and molecular weight above (C₅₀H₆₉N₁₅O₉, ≈1,024.18 g/mol) are independently corroborated across multiple reference sources and should be treated as the reliable figures regardless of which CID a given source cites.
The full molecular identity of MT-2 is confirmed on every Ascend Peptides UK batch by independent LC-MS analysis through Janoshik laboratory. The complete laboratory quality control workflow is documented on the how we test peptides page.
Relationship to Native Alpha-MSH
Alpha-melanocyte-stimulating hormone (alpha-MSH) is an endogenous 13-amino-acid linear peptide derived by proteolytic cleavage from the precursor protein proopiomelanocortin (POMC). Within the alpha-MSH sequence, a central four-residue segment — His-Phe-Arg-Trp — is recognised in the pharmacology literature as the “message sequence”: the minimal core responsible for melanocortin receptor activation, with the residues flanking it modulating potency, selectivity and stability rather than receptor recognition itself.
MT-2 was designed around this message sequence. It retains the His-Phe-Arg-Trp core — with an unnatural D-phenylalanine substituted for the natural L-phenylalanine at the position corresponding to residue 7 of the native alpha-MSH sequence — while truncating the rest of the native 13-residue chain and adding a norleucine substitution at the position corresponding to residue 4 of that same native sequence, plus the lactam cyclisation described above. (These position numbers — 4 and 7 — refer throughout to the native alpha-MSH/NDP-MSH numbering convention used in the melanotropin literature, not to sequential positions within the shortened seven-residue MT-2 molecule itself, where the same substituted residues fall at different positions.) The result is a much shorter, conformationally constrained molecule that preserves — and in the published pharmacology literature, enhances — engagement with the melanocortin receptor family, rather than a simple fragment or shortened copy of alpha-MSH.
The Melanocortin Receptor Family
The melanocortin receptors are a family of five G-protein-coupled receptor subtypes, MC1R through MC5R, each with a distinct tissue distribution and association with different areas of published research. Understanding which subtypes a given compound engages is essential context for interpreting any experimental result obtained with it.
|
Receptor |
Primary Tissue Distribution |
Associated Research Area |
MT-2 Activity |
|---|---|---|---|
|
MC1R |
Melanocytes, skin |
Pigmentation and melanogenesis pathway research |
Agonist |
|
MC2R |
Adrenal cortex |
ACTH-specific signalling |
No reported activity |
|
MC3R |
Brain, gastrointestinal tract, immune cells |
Energy homeostasis and immune-modulation research |
Agonist |
|
MC4R |
Hypothalamus and other CNS nuclei |
Energy homeostasis and appetite-signalling research |
Agonist |
|
MC5R |
Exocrine glands, immune tissue |
Exocrine secretion and immune-signalling research |
Agonist |
MC2R is the outlier in this family: it is selective for adrenocorticotropic hormone (ACTH) rather than alpha-MSH-derived ligands, and MT-2 is not reported to engage it. Across the other four subtypes, MT-2’s defining pharmacological property is that it does not discriminate between them — it is a non-selective agonist rather than a subtype-selective one.
MT-2 as a Non-Selective Agonist: Binding and Downstream Signalling
All five melanocortin receptors are G-protein-coupled receptors (GPCRs) that, upon agonist binding, couple predominantly to the Gs pathway, stimulating adenylate cyclase, raising intracellular cyclic AMP (cAMP), and activating protein kinase A (PKA). This cAMP/PKA cascade is the shared downstream signalling mechanism across MC1R, MC3R, MC4R and MC5R, and it is this shared mechanism — engaged simultaneously at four receptor subtypes — that MT-2 activates when bound to its research target cells.
Because MT-2 does not distinguish between receptor subtypes, any experimental observation made with MT-2 reflects the combined contribution of every melanocortin receptor subtype expressed in the system under study. Where an experimental design requires attributing an outcome to one receptor subtype specifically, a subtype-selective compound is the appropriate research tool instead. Ascend Peptides UK supplies MT-1 (Afamelanotide), a linear alpha-MSH analogue reported to act preferentially at MC1R, as a selective comparator for MC1R-specific research designs. MT-1’s own structure and regulatory history are covered in a separate guide and are not restated here.
Why Cyclisation Changes Receptor Behaviour
The lactam-bridge cyclisation that distinguishes MT-2 from linear alpha-MSH fragment analogues is not a cosmetic modification. Constraining the peptide backbone into a ring reduces the number of conformations the molecule can adopt in solution, which published structure-activity work on cyclic melanotropin analogues associates with improved receptor-binding potency and greater resistance to proteolytic (enzymatic) degradation relative to comparable linear fragments (Al-Obeidi et al., 1989). This structural principle — conformational constraint via cyclisation improving potency and stability — is a well-established theme in melanotropin peptide design and is why MT-2 and related cyclic lactam analogues occupy a distinct position in the melanocortin research-tool literature relative to linear alpha-MSH fragments.
Research Context: Where MT-2 Fits in Melanocortin Research
MT-2’s non-selective, multi-receptor engagement profile makes it a research tool suited to studying the melanocortin system as an integrated network rather than a single pathway in isolation. Published and ongoing research areas associated with the compound’s receptor profile include melanocortin receptor pharmacology and comparative agonist studies (frequently alongside a selective compound such as MT-1 as a comparator), pigmentation and melanogenesis pathway research via MC1R, energy-homeostasis and appetite-signalling research via MC4R in hypothalamic and CNS models, and immune-modulation research via MC3R and MC5R.
Researchers building comparative melanocortin research programmes may also find the MT-1 (Afamelanotide) research line relevant as a receptor-selective comparator compound.
Evidence Base and Research Limitations
Researchers designing experiments around MT-2 should be aware of some specific limits to the current evidence base:
-
MT-2’s non-selectivity means that, unlike a subtype-selective compound, any single experimental outcome cannot be attributed to one melanocortin receptor in isolation without additional controls (for example, receptor-subtype knockdown/knockout models or subtype-selective antagonists) built into the experimental design.
-
Unlike MT-1 (Afamelanotide), which has received regulatory approval in certain jurisdictions for a specific clinical indication, MT-2 has not received equivalent regulatory approval from the MHRA, EMA or any comparable medicines authority. There is no licensed clinical formulation of MT-2, and its evidence base sits predominantly in preclinical and early-phase pharmacology literature rather than an extensive licensed-medicine clinical dataset.
-
Some early human pharmacology literature on MT-2 exists in the published record (Dorr et al., 1996) — cited here for completeness of the evidence-base picture only. This guide does not summarise its dosing, administration route or reported effects, as that falls outside the research-mechanism scope of this page and outside what Ascend Peptides UK documentation covers.
-
The conformational and stability advantages associated with cyclisation (Al-Obeidi et al., 1989) were characterised using the broader class of cyclic lactam melanotropin analogues; researchers should treat compound-specific claims about MT-2 itself, rather than the class generally, with appropriate care and verify against primary literature for their specific research application.
These limitations are a normal feature of an actively studied research compound rather than a reason to dismiss MT-2’s research relevance — they are simply the context a rigorous experimental design should account for.
Analytical and Verification Considerations
MT-2 and other melanocortin peptides are noted on this site’s own documentation as being among the more heavily counterfeited compounds in the UK research peptide market, which makes independent analytical verification particularly important. The core verification methods relevant to MT-2 are HPLC purity analysis and LC-MS molecular identity confirmation — HPLC establishes how pure the supplied material is, while LC-MS confirms that the pure material is actually the target 1,024.18 g/mol cyclic heptapeptide rather than a substituted compound of similar chromatographic behaviour. The complete verification framework is set out on the batch verification page, and the full definition of what “research-grade” means in UK laboratory peptide supply is set out on the research grade standards page.
Storage Note
MT-2 follows the standard lyophilised-peptide storage protocol used across the Ascend Peptides UK catalogue. Full storage, reconstitution and handling detail — including solvent selection and aliquoting practice — is covered in depth in the peptide storage guide and the reconstitution guide, rather than repeated here.
MT-2 Research Resources at Ascend Peptides UK
This page covers MT-2 as a research compound — its structure, mechanism and receptor pharmacology. For product specification, pricing and detailed laboratory application guidance, see the dedicated resources below.
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MT-2 10mg (Melanotan II) — the standalone product listing.
-
MT2 10mg research guide — practical laboratory application reference and MT-1/MT-2 comparison.
MT-2 is one compound within the wider Skin & Cellular Research Peptides UK range, itself part of the complete research peptides UK catalogue.
What Is MT-2? Frequently Asked Questions
What is MT-2?
MT-2 (Melanotan II) is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (alpha-MSH). It is a non-selective melanocortin receptor agonist, engaging MC1R, MC3R, MC4R and MC5R, and is supplied strictly for in-vitro laboratory research.
Is MT-2 the same thing as alpha-MSH?
No. MT-2 is a synthetic analogue derived from alpha-MSH’s sequence, not alpha-MSH itself. It retains the central His-Phe-Arg-Trp “message sequence” responsible for melanocortin receptor activation but is substantially modified: truncated to seven residues, cyclised via a lactam bridge, and carrying a norleucine substitution and a D-phenylalanine substitution not present in the native hormone.
Is MT-2 a cyclic or linear peptide?
MT-2 is cyclic. A lactam (amide) bridge links the sidechains of an aspartic acid and a lysine residue within the sequence, closing the peptide into a ring. This is a defining structural difference from linear alpha-MSH analogues.
Which melanocortin receptors does MT-2 activate?
MT-2 is reported to act as an agonist at four of the five melanocortin receptor subtypes: MC1R, MC3R, MC4R and MC5R. It is not reported to engage MC2R, which is selective for ACTH rather than alpha-MSH-derived ligands.
What are the molecular identifiers for MT-2?
MT-2 has a molecular formula of C₅₀H₆₉N₁₅O₉ and a molecular weight of approximately 1,024.18 g/mol. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂, where the cyclo brackets denote the lactam-bridge cyclisation between the aspartic acid and lysine residues.
What is the difference between a selective and a non-selective melanocortin agonist?
A selective agonist engages predominantly one receptor subtype, allowing that subtype’s contribution to an experimental outcome to be isolated. A non-selective agonist such as MT-2 engages multiple subtypes simultaneously, which is useful for studying the melanocortin system as an integrated network but means individual receptor contributions cannot be isolated without additional experimental controls.
Has MT-2 received regulatory approval?
No. MT-2 has not received approval from the MHRA, EMA or any comparable medicines authority, and there is no licensed clinical formulation of MT-2. Its evidence base is predominantly preclinical and early-phase pharmacology literature.
What is the MHRA status of MT-2 in the UK?
MT-2 supplied by Ascend Peptides UK is not licensed as a medicinal product under the UK Human Medicines Regulations 2012. It is supplied strictly for in-vitro laboratory research. The Medicines and Healthcare products Regulatory Agency (MHRA) is the relevant UK medicines regulator.
Scientific References
Al-Obeidi, F., Castrucci, A.M., Hadley, M.E., & Hruby, V.J. (1989). “Potent and prolonged-acting cyclic lactam analogs of α-melanotropin: design based on molecular dynamics.” Journal of Medicinal Chemistry, 32(12), 2555–2561. — the primary structural design work underlying the cyclic lactam melanotropin scaffold referenced above.
Dorr, R.T., Lines, R., Levine, N., Brooks, C., Xiang, L., Hruby, V.J., & Hadley, M.E. (1996). “Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study.” Life Sciences, 58(20), 1777–1784. — cited for completeness of the evidence-base picture; dosing, administration and reported effects from this study are not reproduced on this page.
National Center for Biotechnology Information. PubChem Compound Summary for CID 92432, Melanotan-II. PubChem. — molecular formula and weight reference.
RESEARCH USE ONLY
All products supplied by Ascend Peptides UK are intended strictly for in-vitro laboratory research purposes only. MT-2 is not a licensed medicinal product under the UK Human Medicines Regulations 2012, and is not for human or veterinary use. No dosing or administration guidelines are provided. Purchasers must be 18 years of age or older and must confirm that products are being purchased solely for lawful laboratory research purposes. Ascend Peptides UK reserves the right to request additional information regarding intended research use and to decline orders where appropriate.
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