Melanotan 1, Melanotan 2 and PT-141 are synthetic analogues of alpha-melanocyte-stimulating hormone, and all three are agonists at melanocortin receptors. They differ in shape and in which receptors they favour. Melanotan 1 is a linear 13-residue peptide. Melanotan 2 and PT-141 are cyclic heptapeptides that share one ring and differ at the C-terminus.
At a glance
| Melanotan 1 | Melanotan 2 | PT-141 | |
|---|---|---|---|
| Shape | Linear | Cyclic, lactam bridge | Cyclic, lactam bridge |
| Length | 13 amino acids | 7 amino acids | 7 amino acids |
| Relation to alpha-MSH | Full length with Nle4 and D-Phe7 | Shortened core with the same two substitutions | The Melanotan 2 ring |
| C-terminus | Amide | Amide | Free acid |
| Receptor profile | Highest affinity at MC1R | Agonist across MC1R, MC3R, MC4R and MC5R | Agonist across MC1R, MC3R, MC4R and MC5R |
| NuVion vial size | 10mg | 10mg | 10mg |
Structure
Alpha-MSH is a 13-residue hormone. Melanotan 1 keeps its full length and swaps two residues: methionine at position 4 becomes norleucine, which cannot be oxidised, and phenylalanine at position 7 becomes its D-form, which resists peptidases. It is also written as NDP-alpha-MSH.
Melanotan 2 cuts the sequence down to the core that binds the receptor and locks it into a ring with a lactam bridge between an aspartate and a lysine side chain. PT-141 has the same ring. The only difference is the C-terminus, which is an amide in Melanotan 2 and a free carboxylic acid in PT-141.
Mechanism at the receptor level
The melanocortin receptors are a family of five G protein-coupled receptors that signal through Gs and cyclic AMP. Melanotan 1 binds MC1R most strongly, the receptor expressed on melanocytes. The cyclic analogues are less selective and activate MC1R, MC3R, MC4R and MC5R. In the laboratory the three are used together to compare a linear ligand with constrained ones across receptor subtypes.
Where each is used in research
- Melanotan 1: MC1R binding and cyclic AMP assays in melanocyte cultures
- Melanotan 2: non-selective reference agonist in melanocortin receptor panels
- PT-141: MC3R and MC4R signalling assays in transfected cell lines
- All three: structure-activity comparisons of linear and cyclic melanocortin ligands
Supplied by NuVion
NuVion stocks Melanotan 1, Melanotan 2 and PT-141 in Australia as 10mg lyophilised vials. Published certificates are shown on each product page and in the COA library.
Frequently asked questions
What is the difference between Melanotan 1 and Melanotan 2?
Melanotan 1 is a linear 13-residue analogue of alpha-MSH with its highest affinity at MC1R. Melanotan 2 is a cyclic 7-residue analogue that activates four of the five melanocortin receptors.
Is PT-141 the same as Melanotan 2?
No, though they are close. Both have the same cyclic heptapeptide ring. PT-141 ends in a free acid where Melanotan 2 ends in an amide.
Are these products therapeutic goods in Australia?
No. NuVion’s Melanotan 1, Melanotan 2 and PT-141 are laboratory chemicals for in vitro research. They are not included in the Australian Register of Therapeutic Goods, have not been assessed by the Therapeutic Goods Administration, and are not for human or veterinary use.
Research use only. These products are laboratory chemicals supplied for in vitro research. They are not included in the Australian Register of Therapeutic Goods and have not been assessed by the Therapeutic Goods Administration for quality, safety or efficacy. They are not for human or veterinary use, and nothing on this page is a representation about therapeutic use.