What Is MT-2 (Melanotan II)? Research Overview

MT-2, written in full as Melanotan II, is a synthetic peptide in the melanocortin research family. Like MT-1, it's an analog of alpha-melanocyte-stimulating hormone (α-MSH), but it's built very differently: a short cyclic peptide rather than a linear one, and far less selective about which melanocortin receptor it activates. This overview explains what MT-2 is, how it works at the receptor level, and where it's used in melanogenesis and melanocortin-pharmacology research. For in-vitro laboratory research only.

What is MT-2 (Melanotan II)?

MT2, MT-II and Melanotan 2 all name the same compound: a cyclic heptapeptide written Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. Six of its seven residues form a ring, closed by a lactam bridge, an amide bond between the side chains of aspartic acid and lysine. Inside that ring sits His-Phe-Arg-Trp, the four-residue core α-MSH uses to bind melanocortin receptors, with phenylalanine in its mirror-image D-form. The Melanotan-2 (MT-2) reference standard is catalogued under CAS 121062-08-6 and supplied lyophilized in 10mg research vials.

Why the cyclic structure matters

Cyclization is the central design idea behind MT-2. Native α-MSH is a flexible linear chain that peptidases break down quickly. Locking the core into a ring constrains it into a shape the receptors recognize and, together with the D-phenylalanine, makes the molecule more resistant to enzymatic breakdown. The same constraint is associated with high potency across several melanocortin receptors, which is why MT-2 serves as a broad reference agonist rather than a receptor-specific one.

How does Melanotan 2 work? Melanocortin receptor pharmacology

The melanocortin system has five G-protein-coupled receptors, MC1R through MC5R. Endogenous melanocortins such as α-MSH act at most of them; MC2R is the exception, responding to ACTH. MT-2 is studied as a non-selective agonist that acts across MC1R, MC3R and MC4R, and that breadth is the key pharmacological difference from the MC1R-preferring MT-1. The three receptors most discussed in MT-2 research are:

• MC1R: expressed on melanocytes, where it drives the cAMP signaling that controls melanin synthesis
• MC3R: expressed in the brain, particularly the hypothalamus, and in some peripheral tissues
• MC4R: expressed mainly in the central nervous system, including the hypothalamus

All three raise intracellular cyclic AMP (cAMP) when activated, so cAMP accumulation is the standard functional readout in receptor assays. Binding and cAMP studies in cell lines engineered to express a single receptor subtype are how MT-2's activity profile is characterized and compared with other analogs.

MC1R and melanogenesis models

At MC1R on melanocytes, MT-2 engages the same cascade described for MT-1: cAMP activates protein kinase A, which phosphorylates CREB and drives expression of MITF, the master regulator of the melanogenic enzymes tyrosinase, TYRP1 and DCT. Readouts in cultured melanocytes and melanoma cell lines, such as murine B16 cells, include melanin content, tyrosinase activity and the eumelanin-to-pheomelanin ratio. The MT-1 overview walks through this pathway step by step.

Central MC3R and MC4R signaling

Because MC3R and MC4R are expressed largely in the brain, MT-2 research also reaches into central melanocortin pharmacology. There it serves as a reference agonist for characterizing the receptors themselves: binding affinity, cAMP signaling, and comparison with endogenous ligands, including agouti-related protein (AgRP), which antagonizes MC3R and MC4R. A well-known structure-function example is SHU9119, which differs from MT-2 only by replacing D-phenylalanine with the bulkier D-naphthylalanine. That single change makes it an MC3R and MC4R antagonist, so the MT-2 and SHU9119 pair is a standard tool for probing these receptors.

What is MT-2 studied for in research?

The MT-2 research peptide is a reference compound wherever a study needs to activate several melanocortin receptors at once, or to compare a broad agonist with a selective one. Common research themes include:

• Melanogenesis assays in cultured melanocytes and melanoma cell lines: melanin content, tyrosinase activity and MITF expression
• Receptor-selectivity studies comparing MT-2's broad profile with the MC1R-preferring MT-1
• MC3R and MC4R binding and cAMP-signaling assays in receptor-expressing cell lines
• Structure-function work on cyclic melanocortin analogs, including substitutions at the D-Phe position

For the wider melanocortin family, see the pigmentation research peptides overview; for the matrix side of skin biology, the GHK-Cu research guide; and for the full category, best peptides for skin research.

MT-2 vs MT-1: the short version

Melanotan 2 vs 1 comes down to structure and selectivity. MT-1 is a linear 13-residue α-MSH analog studied mainly at MC1R; MT-2 is a cyclic seven-residue analog that acts across MC1R, MC3R and MC4R. A study isolating MC1R signaling in melanocytes fits MT-1, while one probing the melanocortin system across receptor subtypes fits MT-2. Neither is a stronger version of the other. The full comparison is in what is MT-1.

MT-2 half-life and stability

Questions about MT-2's half-life usually trace back to its design: the ring and the D-phenylalanine make it more resistant to peptidases than native α-MSH. Published pharmacokinetic figures depend on formulation and model and don't transfer to research material, so we don't reproduce them here. For in-vitro work the practical questions are storage and handling: keep lyophilized MT-2 cold, dry and out of light until reconstitution. See how to store research peptides.

How MT-2 is supplied

Eon supplies MT-2 lyophilized in 10mg research vials, shipped from our US facility with tracking and a printed lot number on each vial. Reconstitute for in-vitro use with bacteriostatic water following how to reconstitute peptides; the MT-2 reconstitution calculator returns concentration for each diluent volume. Order Melanotan-2 (MT-2) directly or compare it across the cosmetic & skin research category.