What Is MT-1 (Melanotan I)? Research Overview

MT-1, also written Melanotan I or Melanotan-1, is the most widely studied synthetic analog in pigmentation research. It is a modified form of alpha-melanocyte-stimulating hormone (α-MSH), the endogenous peptide that signals to melanocytes, engineered to resist enzymatic breakdown and to act preferentially at the melanocortin-1 receptor (MC1R). This overview explains what MT-1 is, how it works in melanocyte models, and how it differs from MT-2 — the comparison most searches about it are really asking. For in-vitro laboratory research only.

What is MT-1 (Melanotan I)?

MT-1 is the research name for afamelanotide, a synthetic peptide with the α-MSH sequence carrying two substitutions — written [Nle4, D-Phe7]-α-MSH. Like the native hormone, it is a linear chain of 13 amino acids. Its research record stretches back several decades, which gives it one of the deepest methodological bases among pigmentation-research peptides. The Melanotan-1 (MT-1) reference standard is catalogued under CAS 75921-69-6 and supplied lyophilized in 5mg research vials.

Where α-MSH comes from

Native α-MSH is a 13-residue peptide cleaved from pro-opiomelanocortin (POMC), the same precursor protein that gives rise to ACTH and β-endorphin. It belongs to the melanocortins, a family of peptides that act at five melanocortin receptors, MC1R through MC5R. In skin biology, α-MSH is a key endogenous agonist at MC1R on melanocytes, the cells that synthesize melanin pigment.

Why the Nle4 and D-Phe7 substitutions matter

The two changes are what turn a short-lived hormone into a stable research tool. Replacing methionine at position 4 with norleucine removes an oxidation-prone sulfur atom while keeping a similar side chain. Swapping L-phenylalanine at position 7 for its mirror-image D-form makes that stretch of the chain harder for peptidases to cleave and is associated with higher receptor potency. In early bioassays the analog showed more potent and longer-lasting activity than native α-MSH, which is the basis of its use as a reference agonist in melanocortin research.

How does Melanotan 1 work? The MC1R pathway

MC1R is a G-protein-coupled receptor on the melanocyte surface. When an agonist such as α-MSH or MT-1 binds it, the receptor activates adenylyl cyclase and raises intracellular cyclic AMP (cAMP). In cultured melanocyte models that signal is traced through a well-characterized cascade:

• cAMP activates protein kinase A (PKA), which phosphorylates the transcription factor CREB
• CREB drives expression of MITF (microphthalmia-associated transcription factor), the master regulator of melanocyte genes
• MITF upregulates the melanogenic enzymes tyrosinase, TYRP1, and dopachrome tautomerase (DCT)
• Tyrosinase catalyzes the rate-limiting steps that convert tyrosine into melanin precursors inside melanosomes

MC1R signaling also shifts which pigment a melanocyte makes. Strong MC1R signaling favors eumelanin, the brown-black pigment, while weak signaling favors pheomelanin, the red-yellow pigment. That eumelanin-to-pheomelanin ratio is a standard readout in pigmentation studies.

What is MT-1 studied for in research?

Because it is a stable, MC1R-preferring agonist, the MT-1 research peptide serves as a reference compound wherever a study needs to activate the MC1R pathway in a controlled way. Common research themes include:

• Melanogenesis assays in cultured melanocytes and melanoma cell lines — melanin content, tyrosinase activity, and MITF expression
• MC1R pharmacology — receptor binding, cAMP signaling, and comparisons with native α-MSH and other melanocortin analogs
• MC1R variant research — how common receptor variants associated with red hair and fair skin alter signaling in cell models
• Pigment-type studies — eumelanin versus pheomelanin synthesis in melanocyte cultures

MT-1 pairs naturally with GHK-Cu in skin-biology research programs: GHK-Cu covers collagen synthesis and matrix remodeling, while MT-1 covers the pigmentation pathway. See the GHK-Cu research guide for the matrix side, the pigmentation research peptides overview for the wider melanocortin family, and best peptides for skin research for the full category.

MT-1 vs MT-2: what's the difference?

Melanotan 1 vs 2 is the most-searched question about this compound, and the answer is structural. Both are synthetic melanocortin agonists derived from α-MSH, but they are built differently and engage different sets of receptors:

• Structure — MT-1 is a linear 13-amino-acid peptide: the full α-MSH sequence with two substitutions. MT-2 (Melanotan II) is a cyclic seven-residue peptide, a lactam-bridged ring built around the shorter His-Phe-Arg-Trp core of α-MSH.
• Receptor profile — MT-1 is studied as an MC1R-preferring agonist. MT-2 is less receptor-selective, acting across a broader set of melanocortin receptors that includes MC1R, MC3R, and MC4R.
• Research focus — MT-1's narrower profile keeps it centered on melanocyte and pigmentation models. Because MC3R and MC4R are expressed largely in the brain, MT-2 research also extends into central melanocortin signaling.

So which is better for research, MT-1 or MT-2? It depends on the question. A study that needs to isolate MC1R signaling in melanocytes is better matched to the more receptor-preferring linear analog, MT-1, while a study of the melanocortin system across several receptor subtypes may call for the broader cyclic one, MT-2. Neither is a stronger version of the other; they are different tools for different receptor questions.

MT-1 half-life and stability

Questions about MT-1's half-life usually trace back to its design. Native α-MSH is broken down quickly by peptidases; the Nle4 and D-Phe7 substitutions make MT-1 markedly more resistant to that degradation, which is why it showed prolonged activity in early bioassays. Published pharmacokinetic figures for afamelanotide depend on formulation and model and do not transfer to research material, so we don't reproduce them here. For in-vitro work the practical stability questions are storage and handling: keep lyophilized MT-1 cold, dry, and out of light until reconstitution — see how to store research peptides.

How MT-1 is supplied

Eon supplies MT-1 lyophilized in 5mg 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-1 reconstitution calculator returns concentration for each diluent volume. Order MT-1 directly or compare it across the cosmetic & skin research category.