The short version of MC1R fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-07-16. Anything still debated is marked as such rather than presented as settled.
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.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
| 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 |
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
=== Membrane contact sites and cell migration === Beyond its biosynthetic and homeostatic roles, the endoplasmic reticulum is highly dynamic and forms membrane contact sites with other organelles and the plasma membrane, supporting lipid exchange, Ca2+ signalling and spatial control of signalling pathways. In migrating cells, ER–plasma membrane contact sites can become polarized, forming rear-to-front gradients that help maintain front–back polarity and directional migration. In epithelial monolayers, ER architecture can be reorganized by tissue edge curvature, influencing epithelial migration modes and tissue remodelling dynamics.
POMC, ACTH and β-lipotropin are secreted from corticotropic cells in the anterior lobe (or adenohypophysis) of the pituitary gland in response to the hormone corticotropin-releasing hormone (CRH) released by the hypothalamus. The pre-pro-opiomelanocortin (Pre-POMC) is the precursor of POMC, its cleavage forms POMC. ACTH, on the other hand, is produced from the cleavage of POMC. The removal of the signal peptide during translation produces the 241-amino acid polypeptide POMC, which undergoes a series of post-translational modifications such as phosphorylation and glycosylation before it is proteolytically cleaved by endopeptidases to yield various polypeptide fragments with varying physiological activity. These fragments include:
== Uranium-230 == Uranium-230 is an artificial isotope of uranium with a half-life of 20.8 days. It has potential to be used in targeted alpha therapy. It is prepared from decay of protactinium-230, which is produced from proton irradiation of thorium targets.
Insulin degludec, marketed as Tresiba and approved in 2015, is an ultra-long-acting insulin with a duration of up to 42 hours. It utilizes multi-hexamer formation and albumin binding to provide a steady insulin release with lower intra-individual variability and greater dosing flexibility. Compared to insulin glargine and detemir, degludec offers a reduced risk of nocturnal hypoglycemia and allows dosing intervals of 8 to 40 hours without compromising glycemic control. These advancements have improved diabetes management by providing more stable blood sugar control, fewer hypoglycemic episodes, and greater convenience for patients. Insulin icodec is, as of 2025, the newest and longest-acting insulin analogue. It has a plasma half-life that is more than eight days, meaning it is a once-weekly insulin. It was approved in 2024 and is marketed as Awiqli by Novo Nordisk. Insulin icodec consists of two peptide chains linked by a disulfide bridge. It contains a C20 fatty diacid-containing side chain, which facilitates strong, reversible binding to albumin. Additionally, three amino acid substitutions are introduced to enhance molecular stability, reduce insulin receptor binding, and slow clearance. These modifications collectively contribute to the prolonged half-life.
Sources: en.wikipedia.org
Controversy soon arose over the size of UNTAG's military component, as the member states of the Security Council expected to cover the majority of the costs were irritated by its relatively large size. However, Angola, Zambia, and other states sympathetic to PLAN insisted that a larger force was necessary to ensure that South Africa did not interfere with independence proceedings. Against their objections UNTAG's force levels were reduced from the proposed 7,500 to three battalions of 4,650 troops. This slashed projected expenses by nearly 300 million dollars, but the Security Council did not approve the revised budget until 1 March 1989. The inevitable delay in UNTAG's full deployment ensured there were insufficient personnel prepared to monitor the movement of PLAN and the SADF or their confinement to bases on 1 April 1989, when the permanent cessation in hostilities was to take effect. Secretary-General de Cuéllar urged restraint in the interim on both sides to avoid jeopardising the de facto ceasefire maintained since August 1988 or the 1 April implementation schedule. Nevertheless, PLAN took advantage of the political uncertainty in the weeks following the UNTAG budget debate to begin moving its forces in Angola closer to the border. Since the early 1980s PLAN had consistently stated its intention to establish camps inside South West Africa during any future political transition, a notion rejected with equal consistency by the South African government.
nucleic acid sequence The precise order of consecutively linked nucleotides in a nucleic acid molecule such as DNA or RNA. Long sequences of nucleotides are the principal means by which biological systems store genetic information, and therefore the accurate replication, transcription, and translation of such sequences is of the utmost importance, lest the information be lost or corrupted. Nucleic acid sequences may be equivalently referred to as sequences of nucleotides, nitrogenous bases, nucleobases, or, in duplex molecules, base pairs, and they correspond directly to sequences of codons and amino acids.
Peart has been voted the greatest rock drummer by music fans, critics and fellow musicians, according to Drummerworld. He was also regarded as one of the finest practitioners of the in-concert drum solo. Initially inspired by Keith Moon, Peart absorbed the influence of other rock drummers from the 1960s and 1970s such as Ginger Baker, Carmine Appice, and John Bonham. Incorporation of unusual instruments (for rock drummers of the time) such as the glockenspiel and tubular bells, along with several standard kit elements, helped create a highly varied setup. Continually modified, Peart's drumkit offered an enormous array of percussion instruments for sonic diversity. For two decades Peart honed his technique; each new Rush album introduced an expanded percussive vocabulary. In the 1990s, he reinvented his style with the help of drum coach Freddie Gruber. Peart served as Rush's primary lyricist, attracting attention over the years for his eclectic style. During the band's early years, Peart's lyrics were largely fantasy/science fiction-focused, though after 1980 he focused more on social, emotional, and humanitarian issues. In 2007, he was placed second on Blender magazine's list of the "40 Worst Lyricists in Rock". In contrast, AllMusic has called Peart "one of rock's most accomplished lyricists", Gibson.com describes Rush's lyrics as "great", and others have called the lyrics "brilliant".
== Research and partnerships == Mondobiotech investigated whether information already published about naturally occurring human substances could suggest new uses in rare diseases. A 2010 case study by researchers at the University of St. Gallen described its use of scientific literature, external researchers and laboratories, and licensing partners instead of maintaining a conventional in-house laboratory operation. Financial news reporting also described the company's approach as searching medical databases for drug candidates and licensing rights to other companies. In 2002, Mondobiotech and InterMune agreed to collaborate on interferon gamma-1b research for pulmonary diseases, including asthma; the arrangement also covered specified patent rights relating to idiopathic pulmonary fibrosis. In 2006, Biogen Idec licensed rights to develop aviptadil for pulmonary arterial hypertension. The agreement included a US$7.5 million upfront payment and up to US$30 million in possible development and commercialization milestones; the milestone amount was conditional, not a payment already received. Biogen stated in a later regulatory filing that it ended its participation in the aviptadil development program in December 2009. In February 2010, Mondobiotech entered a partnership with Lung Rx, a subsidiary of United Therapeutics, for further development of aviptadil. The company also agreed in 2009 to have Bachem develop and manufacture peptides for its research programs.
=== Class II === The heme group in class II cytochrome c proteins is attached to a C-terminal binding motif. The structural fold of class II c-type cytochromes contains a four α-helix bundle with the covalently attached heme group at its core. Representatives of class II are the high-spin cytochrome c' and a number of low-spin cytochromes c, e.g. cyt c556. The cyt c' are capable of binding such ligands as CO, NO or CN−, albeit with rate and equilibrium constants 100 to 1,000,000-fold smaller than other high-spin hemeproteins. This, coupled with its relatively low redox potential, makes it unlikely that cyt c' is a terminal oxidase. Thus cyt c' probably functions as an electron transfer protein. The 3D structures of a number of cyt c' have been determined which show that the proteins usually exist as a dimer. The Chromatium vinosum cyt c' exhibits dimer dissociation upon ligand binding.
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.
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.