This is a working overview of melanocortin receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-06-12 and is reviewed periodically as new material appears.
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.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
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-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
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.
| 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 |
== Etymology == The etymology of the common name "emu" is uncertain, but is thought to have come from an Arabic word for large bird that was later used by Portuguese explorers to describe the related cassowary in Australia and New Guinea. Another theory is that it comes from the word "ema", which is used in Portuguese to denote a large bird akin to an ostrich or crane. In Victoria, some terms for the emu were Barrimal in the Dja Dja Wurrung language, myoure in Gunai, and courn in Jardwadjali. The birds were known as murawung or birabayin to the local Eora and Darug inhabitants of the Sydney basin.
== History == Methylene blue has been described as "the first fully synthetic drug used in medicine". Methylene blue was first prepared in 1876 by German chemist Heinrich Caro. Its use in the treatment of malaria was pioneered by Paul Guttmann and Paul Ehrlich in 1891. During this period before World War I, researchers like Ehrlich believed that drugs and dyes worked in the same way, by preferentially staining pathogens and possibly harming them. Changing the cell membrane of pathogens is how various drugs work, so the theory was partially correct, although far from complete. Methylene blue continued to be used in World War II, where it was not well-liked by soldiers, who observed, "Even at the loo, we see, we pee, navy blue." It was discovered to be an antidote to carbon monoxide poisoning and cyanide poisoning in 1933 by Matilda Brooks. Methylene blue was the original prototype or lead compound for the design of many antimalarials including chloroquine, antihistamines, and antipsychotics including chlorpromazine.
=== Fluorescent protein tags === The fusion of fluorescent tags to proteins in a host cell is a widely popular technique used in experimental cell and biology research in order to track protein interactions in real time. The first fluorescent tag, green fluorescent protein (GFP), was isolated from Aequorea victoria and is still used frequently in modern research. More recent derivations include photoconvertible fluorescent proteins (PCFPs), which were first isolated from Anthozoa. The most commonly used PCFP is the Kaede fluorescent tag, but the development of Kikume green-red (KikGR) in 2005 offers a brighter signal and more efficient photoconversion. The advantage of using PCFP fluorescent tags is the ability to track the interaction of overlapping biochemical pathways in real time. The tag will change color from green to red once the protein reaches a point of interest in the pathway, and the alternate colored protein can be monitored through the duration of pathway. This technique is especially useful when studying G-protein coupled receptor (GPCR) recycling pathways. The fates of recycled G-protein receptors may either be sent to the plasma membrane to be recycled, marked by a green fluorescent tag, or may be sent to a lysosome for degradation, marked by a red fluorescent tag.
Many different amphibians are neotenic, evolved to retain larval traits (such as external gills) as part of an aquatic lifestyle. For example, Ambystoma mexicanum, an extant salamander, is difficult to tell apart from the Permian temnospondyl Branchiosaurus.
== Further reading == Buckley RH (2004). "Molecular defects in human severe combined immunodeficiency and approaches to immune reconstitution". Annu Rev Immunol. 22: 625–55. doi:10.1146/annurev.immunol.22.012703.104614. PMID 15032591. Chinen J, Puck JM (2004). "Successes and risks of gene therapy in primary immunodeficiencies". J Allergy Clin Immunol. 113 (4): 595–603, quiz 604. doi:10.1016/j.jaci.2004.01.765. PMID 15100660. Church AC (2002). "X-linked severe combined immunodeficiency". Hosp Med. 63 (11): 676–80. doi:10.12968/hosp.2002.63.11.1914. PMID 12474613. Gennery AR, Cant AJ (2001). "Diagnosis of severe combined immunodeficiency". J Clin Pathol. 54 (3): 191–5. doi:10.1136/jcp.54.3.191. PMC 1731376. PMID 11253129.
Sources: en.wikipedia.org
==== Cancer ==== The incidence of lymphoma is increased, although it is uncommon and associated with the chronic inflammation, not the treatment of RA. The risk of non-melanoma skin cancer is increased in people with RA compared to the general population, an association possibly due to the use of immunosuppression agents for treating RA.
== Further reading == Manila, S.; Recan, D.; Sewry, C. A.; Hoeltzenbein, M.; Llense, S.; Leturcq, F.; Deburgrave, N.; Barbot, J.-C.; Man, Nguyen thi (1998-05-01). "Mutations in Emery–Dreifuss Muscular Dystrophy and their Effects on Emerin Protein Expression". Human Molecular Genetics. 7 (5): 855–864. doi:10.1093/hmg/7.5.855. ISSN 0964-6906. PMID 9536090. Ziat, Esma; Bertrand, Anne T. (2015-01-01). "FHL1 protein isoforms in Emery–Dreifuss muscular dystrophy". Orphanet Journal of Rare Diseases. 10 (2): O18. doi:10.1186/1750-1172-10-S2-O18. ISSN 1750-1172. PMC 4652543.
On July 7, 2010, Noriega was convicted by the 11th chamber of the Tribunal Correctionnel de Paris and sentenced to seven years in jail. The prosecutor in the case had sought a ten-year prison term. In addition, the court ordered the seizure of €2.3 million (approximately U.S. $3.6 million) that had long been frozen in Noriega's French bank accounts.
== Genome == The genetic material of HHV-6 is composed of linear (circular during an active infection), double stranded DNA which contains an origin of replication, two 8–10 kb left and right direct repeat termini, and a unique segment that is 143–145kb. The origin of replication (often labeled as "oriLyt" in the literature) is where DNA replication begins. The direct repeat termini (DRL and DRR) possess a repeated TTAGGG sequence, identical to that of human telomeres. Variability in the number of telomeric repeats is observed in the range of 15–180. These termini also contain pac-1 and pac-2 cleavage and packing signals that are conserved among herpesviruses. The unique segment contains seven major core gene blocks (U27–U37, U38–U40, U41–U46, U48–U53, U56–U57, U66EX2–U77, and U81–U82), which is also characteristic of herpesviruses. These conserved genes code for proteins that are involved in replication, cleavage, and packing of the viral genome into a mature virion. Additionally, they code for a number of immunomodulatory proteins. The unique segment also possesses a block of genes (U2–U19) that are conserved among HHV-6, HHV-7, and cytomegaloviruses (the betaherpesviruses). A number of the unique segment genes are associated with, for instance, the HCMV US22 family (InterPro: IPR003360). The table below outlines some of their known properties.
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 and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.