The short version of melanocortin receptor fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-09-13. Anything still debated is marked as such rather than presented as settled.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analog of alpha-melanocyte-stimulating hormone |
| Primary receptor family | Melanocortin receptors MC1R through MC5R | Binding is not subtype-selective |
| Development period | 1980s | Synthesized during pigmentation and appetite research |
| Regulatory status | Not an approved medicine | No major regulator has authorized human use |
| Related compound | Afamelanotide | Linear analog studied for photoprotection |
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
== See also == Myanmar Politics of Myanmar List of heads of state of Myanmar List of Burmese monarchs List of heads of state of Myanmar since 1948 List of colonial governors of Burma Vice President of Myanmar Prime Minister of Myanmar List of heads of government of Myanmar since 1948 State Counsellor of Myanmar Lists of office-holders
==== Nonprotein DAMPs ==== Purine metabolites: Nucleotides (e.g., ATP) and nucleosides (e.g., adenosine) that have reached the extracellular space can also serve as danger signals by signaling through purinergic receptors. ATP and adenosine are released in high concentrations after catastrophic disruption of the cell, as occurs in necrotic cell death. Extracellular ATP triggers mast cell degranulation by signaling through P2X7 receptors. Similarly, adenosine triggers degranulation through P1 receptors. Uric acid is also an endogenous danger signal released by injured cells. Adenosine triphosphate (ATP) and uric acid, which are purine metabolites, activate NLR family, pyrin domain containing (NLRP) 3 inflammasomes to induce IL-1β and IL-18.
Chymosin or rennin is a protease found in rennet. It is an aspartic endopeptidase belonging to MEROPS A1 family. It is produced by newborn ruminant animals in the lining of the abomasum to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. It is widely used in the production of cheese. Historically, chymosin was obtained by extracting it from the stomachs of slaughtered calves. Today, most commercial chymosin used in cheese production is produced recombinantly in Escherichia coli, Aspergillus niger var. awamori, and Kluyveromyces lactis.
In 1998, he voted for a bill that would have increased minimum sentencing for possessing a gun while committing a federal crime to ten years in prison, including nonviolent crimes such as marijuana possession. In 2005, Sanders voted for the Protection of Lawful Commerce in Arms Act. The purpose of the act was to prevent firearms manufacturers and dealers from being held liable for negligence when crimes have been committed with their products. As of 2016, he said that he has since changed his position and would vote for legislation to defeat this bill.
=== Writing === Johns described Stargirl as having a similar tone to 1980s films such as E.T. the Extra-Terrestrial and Back to the Future. The start of the series sees the deaths of the original members of the Justice Society of America (JSA). With the younger generation taking up their mantle, Johns said their "paths aren't complete. They don't know where they're going to be or what they're going to be. And so, there's all sorts of mistakes they can make and choices they can make, and who knows what their ultimate destiny will be?... It makes for a lot of fun and a lot of unpredictability". The members of the Injustice Society mirrors those on the JSA team, with Johns teasing that just about everyone who has been a member of the Injustice Society in the comics would appear in the series. Speaking to classic JSA members such as Alan Scott and Jay Garrick, Johns called them the "elderly statesmen" and that they "are spoken of and they exist in the JSA" with "their legacies... felt throughout the show". There were also "plans in the future for things". For the first season, star Brec Bassinger felt the original Doctor Mid-Nite, Charles McNider would have "a significant role to play", while Johns added the season would establish the Seven Soldiers of Victory as the first superhero team before the JSA and explore the history of the Cosmic Staff.
Sources: en.wikipedia.org
In addition to roast beef, deli style sandwiches, called "Market Fresh Sandwiches," are sold at Arby's. The original lineup of sandwiches included Roast Beef and Swiss, Roast Turkey and Swiss, Roast Ham and Swiss, and Roast Chicken Caesar. With the exception of the Chicken Caesar, all Market Fresh Sandwiches came with the standard toppings of spicy brown honey mustard, mayonnaise, red onion rings, green leaf lettuce, tomato slices and sliced Swiss cheese. Additions to the Market Fresh lineup included Roast Turkey Ranch and Bacon and the Ultimate BLT. Market Fresh Five-Star Club, served on Harvest White Bread, was introduced in 2003 for a limited time. The Ultimate BLT was released for a limited time in 2002 and later in 2012. In 2003, the line was again expanded to include other styles of specialty sandwiches that were served on baguettes that included the Italian Beef 'n Provolone, French Dip 'n Swiss, Philly Beef Supreme, and Pot Roast sandwiches. Corned beef and turkey Reuben sandwiches were added to the menu in 2005. In early 2006, Arby's Restaurant Group signed a contract with Pepsi, making Pepsi the chain's exclusive soft drink provider. Franchises which had contracts with Coca-Cola switched to Pepsi-Cola when their contracts with Coca-Cola expired. It was announced in August 2017, that Coca-Cola had won a contract to serve Coke products at all its restaurants, ending an almost 11-year association with Pepsi. The transition began in early 2018, and all Arby's locations were serving Coca-Cola beverages by June 19, 2018.
== Biosynthesis == Elabela gene encodes a pre-proprotein of 54 amino acids, with a signal peptide in the N-terminal region. After translocation into the endoplasmic reticulum and cleavage of the signal peptide, the proprotein of 32 amino acids may generate several active fragments.
=== Stimulants === Stimulants are drugs that usually act on the central nervous system to modulate mental function and behavior, increasing an individual's sense of excitement, decreasing the sensation of fatigue and improving motor coordination. The latter happens via improvement of the interaction between nervous system and musculature. It has greater effect when an athlete is already exhausted - the period when the coordination suffers the most. In the World Anti-Doping Agency list of prohibited substances, stimulants are the second largest class after the anabolic steroids. Benzedrine is a trade name for amphetamine. The Council of Europe says it first appeared in sport at the Berlin Olympics in 1936. It was produced in 1887 and the derivative, Benzedrine, was isolated in the U.S. in 1934 by Gordon Alles. Its perceived effects gave it the street name "speed". British troops used 72 million amphetamine tablets in the Second World War and the RAF got through so many that "Methedrine won the Battle of Britain" according to one report. The problem was that amphetamine leads to a lack of judgement and a willingness to take risks, which in sport could lead to better performances but in fighters and bombers led to more crash landings than the RAF could tolerate. The drug was withdrawn but large stocks remained on the black market. Amphetamine was also used legally as an aid to slimming and also as a thymoleptic before being phased out by the appearance of newer agents in the 1950s.
== Further reading == Blanco, Carlos; Alegría, Analucía A.; Liu, Shang-Min; Secades-Villa, Roberto; Sugaya, Luisa; Davies, Carrie; Nunes, Edward V. (2012). "Differences Among Major Depressive Disorder with and Without Co-occurring Substance Use Disorders and Substance-Induced Depressive Disorder". The Journal of Clinical Psychiatry. 73 (6): 865–873. doi:10.4088/JCP.10m06673. PMID 22480900. Sciacca, Kathleen_2009. "Best Practices for Dual Diagnosis Treatment and Program Development: Co-occurring Mental Illness and Substance Disorders in Various Combinations". In Angela Brown-Miller (ed.). The Praeger International Collection on Addictions. Vol. 3. Praeger. pp. 161–188.{{cite book}}: CS1 maint: numeric names: authors list (link) Sciacca, K. (2011). "Integrated Group Treatment for People Experiencing Mental Health - Substance Use Problems". In David B. Cooper (ed.). Intervention in Mental Health - Substance Use. Radcliffe Pub. pp. 114–127. Sciacca, K.; Hatfield, A. B. (1995). "The Family and the Dually Diagnosed Patient". In Lehman, A. F.; Dixon, L. B. (eds.). Double Jeopardy. Harwood Academic Publishers. pp. 193–209. Giglioti, M. A. (October 1986). "Program Initiatives for Dually-Diagnosed at Harlem Valley Psychiatric Center. Dual Diagnosis -Co-occurring Disorders". New York State Commission on Quality of Care Publication (28). Samet S, Nunes E, Hassin D, et al. (2006). "Diagnosis of comorbid psychiatric disorders in substance users assesses with the Psychiatric Research Interview for Substance and Mental Disorders for DSM-IV". American Journal of Psychiatry.
Sources: en.wikipedia.org
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.
Afamelanotide is a linear analog that has received approval in some jurisdictions for a specific photoprotection indication. Melanotan II is cyclic and less selective across melanocortin receptors. The two are related but are not interchangeable in regulatory or clinical terms.
A compound that activates several receptor subtypes may produce effects beyond pigmentation. Selectivity influences which tissues respond and shapes the side-effect profile described in reports. Designing subtype-selective analogs is a stated goal of melanocortin research.
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.