What Is MT-1 (Melanotan I)?
MT-1 is afamelanotide: a synthetic, linear 13-amino-acid analog of α-melanocyte-stimulating hormone (α-MSH). Two substitutions, norleucine at position 4 and D-phenylalanine at position 7, make it more stable than native α-MSH. It is a potent agonist at MC1R, the receptor on melanocytes, and also activates MC3R, MC4R and MC5R. Because afamelanotide became an approved drug, MT-1 comes with the deepest clinical literature of any melanocortin analog, which is why it is the usual reference compound in melanogenesis and MC1R-signaling research.
What Is MT-2 (Melanotan II)?
MT-2 is a cyclic lactam heptapeptide: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂. Its ring structure keeps the core α-MSH binding motif (His-Phe-Arg-Trp) while making the molecule smaller and more rigid. Like MT-1, it activates MC1R, MC3R, MC4R and MC5R. Its compact cyclic design made it the parent structure of bremelanotide (PT-141), and it is used in research on the central melanocortin system as well as pigmentation.
MT-1 vs MT-2 Side by Side
| Property | MT-1 (Melanotan I) | MT-2 (Melanotan II) |
|---|---|---|
| Other names | Afamelanotide, [Nle⁴, D-Phe⁷]-α-MSH, Melanotan 1 | Melanotan 2, MT2 |
| Structure | Linear | Cyclic lactam |
| Length | 13 amino acids | 7 residues |
| Molecular weight | ~1,647 Da | ~1,024 Da |
| Receptors activated | MC1R, MC3R, MC4R, MC5R | MC1R, MC3R, MC4R, MC5R |
| Best known for | MC1R and melanogenesis research; approved-drug literature | Central melanocortin research; parent of bremelanotide |
| Parent hormone | α-MSH | α-MSH (core motif) |
| Approved drug form | Yes: afamelanotide implant (Scenesse) | None |
| Evo Peptides vial | 10mg lyophilized | 10mg lyophilized |
Use the molecular weight row when checking a COA's mass-spec result. The general method is in How to Read a Peptide COA.
Melanocortin Receptor Activity
The five melanocortin receptors (MC1R to MC5R) are expressed in different tissues, and both compounds activate four of them. Neither binds MC2R, the adrenal ACTH receptor. The practical differences for study design come from structure: MT-2's small cyclic form is more rigid and is the compound historically used to probe central MC3R and MC4R pathways, while MT-1 is the standard reference for MC1R and melanocyte work.
| Receptor | Main tissue studied | MT-1 | MT-2 |
|---|---|---|---|
| MC1R | Melanocytes (pigmentation) | Yes | Yes |
| MC2R | Adrenal cortex (ACTH receptor) | No | No |
| MC3R | Central nervous system | Yes | Yes |
| MC4R | Central nervous system | Yes | Yes |
| MC5R | Exocrine glands | Yes | Yes |
MT-1 and MT-2 Regulatory Status
Afamelanotide, the molecule in MT-1, is approved as a prescription implant (Scenesse) for a rare photosensitivity disorder. MT-2 has no approval anywhere. Research-grade MT-1 and MT-2 are neither of those things: they are laboratory reagents sold for in vitro research only, not for human or veterinary use.
MT-1 and MT-2 Price per mg
| Product | Vial | Price | $ / mg |
|---|---|---|---|
| MT-1 (Melanotan I) | 10mg | $29.95 | $3.00 |
| MT-2 (Melanotan II) | 10mg | $44.95 | $4.50 |
Storage and Handling
- Lyophilized: store sealed and away from light, at −20 °C long-term or 2–8 °C short-term.
- Reconstituted: refrigerate and aliquot to limit freeze-thaw cycles. Use Evo H2O bacteriostatic water and the reconstitution calculator for concentration math.
- Record keeping: log lot number, receipt date and reconstitution date for each vial.
Full details: peptide storage guide.
Glossary
| Term | Definition |
|---|---|
| α-MSH | Alpha-melanocyte-stimulating hormone, the natural 13-amino-acid peptide both compounds are based on. |
| Melanocortin receptor (MC1R–MC5R) | Five G-protein-coupled receptors that respond to α-MSH and related peptides. |
| Melanogenesis | The production of melanin pigment by melanocytes. |
| Cyclic lactam | A ring formed by an amide bond between two side chains, which makes a peptide more rigid and stable. |
| RUO | Research Use Only: sold for laboratory research, not for human or veterinary use. |
Frequently Asked Questions
What is the difference between MT-1 and MT-2?
What is MT-1?
What is MT-2?
Is MT-1 the same as afamelanotide?
Which melanocortin receptors do MT-1 and MT-2 bind?
Is MT-2 FDA-approved?
How much do MT-1 and MT-2 cost?
What molecular weight should an MT-1 or MT-2 COA show?
How should MT-1 and MT-2 be stored?
Are MT-1 and MT-2 for human use?
Sources
- Structures and sequences: afamelanotide ([Nle⁴, D-Phe⁷]-α-MSH) and Melanotan II (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂) as published in the peptide chemistry literature.
- Regulatory: afamelanotide implant approved by the U.S. FDA in 2019 and by the European Medicines Agency in 2014.
- Evo Peptides product data: MT-1 10mg and MT-2 10mg, prices as of September 26, 2026.