Melanotan II is a synthetic cyclic heptapeptide analog of α-MSH, a naturally occurring peptide that regulates pigmentation through target receptor activation. Originally developed as a research compound for studying melanogenesis and photoprotective pathways, MT-II exhibits high affinity for its primary target receptor subtypes. Through selective binding to multiple pathway targets, it has been examined in research contexts involving pigmentation pathways, endocrine signaling, and peptide-receptor pharmacology in laboratory settings.

MT-II belongs to the melanocortin peptide family and was originally developed as a pharmacological tool compound for studying melanocortin receptor biology and melanogenesis pathways. Its cyclic structure formed by a lactam bridge between residues is what distinguishes it from linear α-MSH and contributes to its improved metabolic stability and receptor potency in laboratory models.

What makes MT-II particularly valuable as a research compound is its non-selective activity across the melanocortin receptor family. Where α-MSH shows preferential MC1R engagement, MT-II demonstrates measurable affinity at MC1R, MC3R, and MC4R — making it a useful probe for comparative receptor subtype studies and signaling pathway dissection across multiple research domains.

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• CAS Number: 121062-08-6
• Molecular Weight: 1024.18 Da
• Purity: ≥99%
• Also Known As: MT-II, MT-2, Melanotan 2, Ac-Nle4-cyclo[Asp5,D-Phe7,Lys10]alpha-MSH(4-10)-NH2
• Chemical Formula: C₅₀H₆₉N₁₅O₉

In cell-based and preclinical models, MT-II acts as a non-selective melanocortin receptor agonist, binding with high affinity across multiple receptor subtypes. Radioligand competition assays have characterized its binding profile as: MC1R (Ki ~0.2 nM), MC3R (Ki ~0.3 nM), and MC4R (Ki ~0.6 nM), with substantially lower affinity at MC2R and MC5R. Functional assays confirm MT-II behaves as a full agonist at MC1R and MC4R, and a partial agonist at MC3R.

At MC1R, receptor activation triggers intracellular cAMP accumulation and PKA-dependent phosphorylation of CREB — a transcription factor that drives expression of MITF, which in turn upregulates tyrosinase, the rate-limiting enzyme in melanin biosynthesis. This signaling cascade has been characterized in B16-F10 melanoma cells and primary human melanocyte preparations, where MT-II produces melanin increases at concentrations approximately 10-fold lower than α-MSH.

Its cyclic conformation confers conformational rigidity relative to the linear parent peptide, contributing to the enhanced receptor affinity and metabolic stability observed across in-vitro assay systems.

• Melanocortin Receptor Profiling
• cAMP Signaling Research
• Receptor Subtype Selectivity Studies
• Peptide Conformational Stability Research
• Endocrine Signaling Models