If you have been reading about melanocortin receptor and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-01-07. Numbers and descriptions here follow the published literature rather than marketing material.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
=== Works cited === Bowen, Michael (2011). The Roots of Modern Conservatism: Dewey, Taft, and the Battle for the Soul of the Republican Party. UNC Press Books. ISBN 9780807869192. McCoy, Donald R. (1984). The Presidency of Harry S. Truman. University Press of Kansas. ISBN 978-0-7006-0252-0.
=== ConSurf === Ben-Tal has led the development of ConSurf, a computational method and web server that uses evolutionary information to identify potentially functionally important regions in proteins. The methodology maps evolutionary conservation scores onto three-dimensional molecular structures, allowing conserved regions of a protein to be visualized on its surface. The original ConSurf work was published in Bioinformatics in 2003 by a team that included Ben-Tal, Fabian Glaser, Tal Pupko, Inbal Paz, Rachel E. Bell, Dalit Bechor-Shental, and Eric Martz. The ConSurf project has subsequently been expanded through successive versions and databases. A 2016 paper described an updated methodology for estimating and visualizing evolutionary conservation in macromolecules, while later work produced ConSurf-DB, a repository containing precomputed evolutionary conservation profiles for proteins with known structures. Ben-Tal has continued to contribute to the development of ConSurf. A 2023 paper described a revised version of the system for using evolutionary information to analyze macromolecules.
During the question and answer section of the paper, Moniz, it is alleged, "startled" Fulton by inquiring if this procedure might be extended to human subjects suffering from mental illness. Fulton stated that he replied that while possible in theory, it was surely "too formidable" an intervention for use on humans.
In humans, the homolog gene, TDH, is a non-functional pseudogene. The loss of an acceptor splice site consistently leads to a non-functional truncated protein. The primary pathway for threonine degradation in humans instead starts with threonine ammonia-lyase (aka threonine dehydratase) and produces propionyl-CoA instead of glycine.
Sources: en.wikipedia.org
Many cell signals are carried by molecules that are released by one cell and move to make contact with another cell. Signaling molecules can belong to several chemical classes: lipids, phospholipids, amino acids, monoamines, proteins, glycoproteins, or gases. Signaling molecules binding surface receptors are generally large and hydrophilic (e.g. TRH, Vasopressin, Acetylcholine), while those entering the cell are generally small and hydrophobic (e.g. glucocorticoids, thyroid hormones, cholecalciferol, retinoic acid), but important exceptions to both are numerous, and the same molecule can act both via surface receptors or in an intracrine manner to different effects. In animal cells, specialized endocrine cells release these hormones and send them through the circulatory system to other parts of the body. They then reach target cells, which can recognize and respond to the hormones and produce a result. This is also known as endocrine signaling. Plant growth regulators, or plant hormones, move through cells or by diffusing through the air as a gas to reach their targets. Hydrogen sulfide is produced in small amounts by some cells of the human body and has a number of biological signaling functions. Only two other such gases are currently known to act as signaling molecules in the human body: nitric oxide and carbon monoxide.
Grades from four quarters of 7th grade and the first quarter of 8th grade (or four quarters of 8th grade and first quarter of 9th grade) in math, science, English, and social studies A standardized reading comprehension test A standardized numerical test All of these are factored into a final score. The number of students admitted into the S/T program vary from each school, but as an example, 225-250 students with the top scores are admitted to Roosevelt's Science and Technology Program. The next 60 students are placed on a waiting list. All interested 8th and 9th grade students who are residents of Prince George's County are eligible to apply for admission to the Science and Technology Center.
=== Clinical findings === TCS is often first suspected with characteristic symptoms observed during a physical exam. The clinical presentation of TCS can resemble other diseases, making diagnosis difficult. The OMENS classification was developed as a comprehensive and stage-based approach to differentiate the diseases. This acronym describes five distinct dysmorphic manifestations, namely orbital asymmetry, mandibular hypoplasia, auricular deformity, nerve development, and soft-tissue disease. Orbital symmetry
Recent research involving MOFs as a drug delivery method includes more than just the encapsulation of everyday drugs like ibuprofen and aspirin. In early 2018 Chen et al., published detailing their work on the use of MOF, ZIF-8 (zeolitic imidazolate framework-8) in antitumor research "to control the release of an autophagy inhibitor, 3-methyladenine (3-MA), and prevent it from dissipating in a large quantity before reaching the target." The group performed in vitro studies and determined that "the autophagy-related proteins and autophagy flux in HeLa cells treated with 3-MA@ZIF-8 NPs show that the autophagosome formation is significantly blocked, which reveals that the pH-sensitive dissociation increases the efficiency of autophagy inhibition at the equivalent concentration of 3-MA." This shows promise for future research and applicability with MOFs as drug delivery methods in the fight against cancer.
The Inter-American Conference of Symbolic Masonry was an international gathering of Freemasons from around the world for the member Grand Lodges and Orients of the Inter-American Masonic Confederation (CMI). The First Inter-American Conference of Symbolic Masonry was hosted in Montevideo in 1947. The second was hosted in Mexico City in 1951. The third was held in Havana. From February 25 to March 8, 1955, Freemasonic delegations from Europe, Asia, and America (e.g.; North America and South America), and their families, landed at Havana to participate in the Third Inter-American Conference of Symbolic Freemasonry. When the delegations arrived at Havana Airport on Friday the 25th, at different prearranged times, they were greeted by the Cuban Marine Corps Band which marched onto the airfield and played the national anthems of the delegations, before they were brought to their hotel for the conference, the Sevilla Biltmore. That night, the delegations were given time to become acquainted with the city of Havana. The delegation from the United States enjoyed an evening at the Tropicana.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.