MT-1 vs MT-2
Melanotan I and Melanotan II are both alpha-MSH analogues, but they behave entirely differently at receptor level. Selectivity is the whole difference.
| MT-1 | MT-2 | |
|---|---|---|
| Receptor profile | Selective for MC1R | Non-selective: MC1R, MC3R, MC4R and MC5R |
| Structure | Linear alpha-MSH analogue | Cyclic alpha-MSH analogue |
| Other names | Afamelanotide | Melanotan II |
| Mechanism studied | Melanogenesis in melanocytes without significant MC3R/MC4R activation | Broad melanocortin agonism across the receptor family |
| Reported half-life | ~1 hour | ~1 hour |
What the difference means
In practice, MT-1 acts only on MC1R. MT-2 acts on the whole melanocortin family, including MC3R and MC4R, which are involved in entirely different physiological systems from pigmentation. That is why they are not interchangeable in an experimental set-up, and why selectivity is the property the literature actually discusses.
Selectivity is the whole point
MC1R is the receptor linked to melanogenesis. MT-1 binds it selectively, which makes the compound a relatively clean tool when the pigmentation pathway alone is to be studied.
MT-2 is cyclic and non-selective. It activates MC1R, but also MC3R, MC4R and MC5R. These receptors sit in other systems, so a set-up using MT-2 cannot attribute observations to MC1R alone.
Why the difference matters methodologically
When a compound acts on four receptors instead of one, cause and effect become harder to isolate. It is a classic methodological trade-off: broader activity gives more observable effects, but weaker inferences about which receptor caused what.
That is why the two are often used side by side, with MT-1 serving as a selective reference against MT-2's broader profile.
Documentation for each batch
Both are supplied lyophilised with a batch number, stated purity and test date on the certificate of analysis.
The material is sold exclusively for research purposes and laboratory use. We provide no dosing, instructions for use or health claims.
Frequently asked questions
What is the difference between Melanotan I and II?
Receptor selectivity. MT-1 is selective for MC1R. MT-2 is non-selective and activates MC1R, MC3R, MC4R and MC5R.
Is MT-1 the same as afamelanotide?
Yes, afamelanotide is the name used for Melanotan I in the literature.
Which one is used in pigmentation research?
Both appear in that literature, but MT-1 is the selective one – it allows MC1R to be studied without simultaneous activation of MC3R and MC4R.
All material is sold exclusively for research purposes and laboratory use. This page gives no dosing, instructions for use or health claims. Read more about safety and regulation.