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 2026-05-14 and is reviewed periodically as new material appears.
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.
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
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 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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic cyclic heptapeptide | Analog of alpha-MSH with an internal lactam bridge |
| Molecular weight | Approximately 1024 daltons | Free base value; salt forms differ |
| Appearance | White to off-white powder | Usually supplied as a lyophilized solid |
| Solubility | Freely soluble in water | Poorly soluble in nonpolar solvents |
| Typical storage | −20 °C, dry, protected from light | Repeated freeze-thaw cycles degrade peptides |
Larson received media attention for scolding members of Congress for shutting down the government on September 30, 2013. Larson was among the 46 Democrats who voted against final passage of the Fiscal Responsibility Act of 2023 in the House.
=== Thioalcohols === 2-Mercaptoethanol is a reagent in biochemistry. 3-Mercaptopropane-1,2-diol is a medicine. These compounds have high solubility in water owing to the presence of OH substituent(s).
==== p27 ==== Another gene that is a target of gene amplification is SKP2. SKP2 is an F-box protein with a role in substrate recognition for ubiquitylation and degradation. SKP2 targets p27Kip-1, an inhibitor of cyclin-dependent kinases (CDKs). CDKs2/4 partner with the cyclins E/D, respectively, forming a family of cell cycle regulators which control cell cycle progression through the G1 phase. Low level of p27Kip-1 protein is often found in various cancers and is due to overactivation of ubiquitin-mediated proteolysis through overexpression of SKP2.
== Menu == Culver's menu consists of butter burgers, chicken sandwiches, chicken tenders, fish, salads, soup, onion rings, french fries, cheese curds, and corn dogs. For dessert, the restaurant offers its frozen custard, served in either a dish, cone, or blended into a concrete mixer, malt, or shake. The company released an April Fools' joke in 2021 showing a large fried cheese curd in a burger bun, naming it the CurderBurger. Soon after the post was made, a change.org petition was created to make the burger a reality, gathering over 600 signatures. In celebration of National Cheese Curd Day on October 15 that year, the CurderBurger debuted, consisting of a large cheese curd on top of a burger patty. Each location only got a limited number of cheese curd patties, and all Madison, Wisconsin restaurants sold out before noon.
Sources: en.wikipedia.org
== Selected publications == Kiessling, Laura L.; Pohl, Nicola L. (1996-02-01). "Strength in numbers: non-natural polyvalent carbohydrate derivatives". Chemistry & Biology. 3 (2): 71–77. doi:10.1016/S1074-5521(96)90280-X. ISSN 1074-5521. PMID 8807830. Ko, Kwang-Seuk; Jaipuri, Firoz A.; Pohl, Nicola L. (2005-09-28). "Fluorous-Based Carbohydrate Microarrays". Journal of the American Chemical Society. 127 (38): 13162–13163. Bibcode:2005JAChS.12713162K. doi:10.1021/ja054811k. ISSN 0002-7863. PMID 16173741. Wacker, Michael; Feldman, Mario F.; Callewaert, Nico; Kowarik, Michael; Clarke, Bradley R.; Pohl, Nicola L.; Hernandez, Marcela; Vines, Enrique D.; Valvano, Miguel A.; Whitfield, Chris; Aebi, Markus (2006-05-02). "Substrate specificity of bacterial oligosaccharyltransferase suggests a common transfer mechanism for the bacterial and eukaryotic systems". Proceedings of the National Academy of Sciences. 103 (18): 7088–7093. Bibcode:2006PNAS..103.7088W. doi:10.1073/pnas.0509207103. ISSN 0027-8424. PMC 1459022. PMID 16641107.
Eric plans to have Jesse to sell his shares to Felim at the shoot, but Harper instead covertly helps Jesse buy a controlling stake in Rican from FutureDawn Partners, a socially conscious investment fund, seeing as Rican is underperforming and hiding it from Felim to ensure his investment. Felim, realizing Eric has yet again failed to deliver on his promises, cuts ties with him for good.
=== Age-appropriate use === Nipples (teats) are typically subdivided by flow rate, with the slowest flow rate recommended for premature infants and infants with feeding difficulties. However, flow rates are not standardised and vary considerably between brands. When the infant is held in someone's arms while being bottle-fed, it receives physical contact, not as close as during breastfeeding, but more than when the bottle is given while lying in bed. Lying on its back, the infant is more likely to choke and misses out on the physical contact that is so important for its development. The NHS recommends a sippy cup or beaker be introduced by 6 months and the use of bottles discontinued by 1 year. The AAP recommends that the cup be introduced by one year of age and that the use of the bottle by discontinued by 18 months. The use of bottles is discouraged beyond two years of age by most health organisations as prolonged use can cause tooth decay. Early childhood caries (ECC) is also a concern when considering how long breastfeeding should continue.
== Mechanism of action == The principal mechanism of the epothilone class is the inhibition of the microtubule function. Microtubules are essential to cell division, and epothilones, therefore, stop cells from properly dividing. Epothilone B possesses the same biological effects as paclitaxel both in vitro and in cultured cells. This is because they share the same binding site, as well as binding affinity to the microtubule. Like paclitaxel, epothilone B binds to the αβ-tubulin heterodimer subunit. Once bound, the rate of αβ-tubulin dissociation decreases, thus stabilizing the microtubules. Furthermore, epothilone B has also been shown to induce tubulin polymerization into microtubules without the presence of GTP. This is caused by the formation of microtubule bundles throughout the cytoplasm. Finally, epothilone B also causes cell cycle arrest at the G2-M transition phase, thus leading to cytotoxicity and eventually cell apoptosis. The ability of epothilone to inhibit spindle function is generally attributed to its suppression of microtubule dynamics; but recent studies have demonstrated that suppression of dynamics occurs at concentrations lower than those needed to block mitosis. At higher antimitotic concentrations, paclitaxel appears to act by suppressing microtubule detachment from centrosomes, a process that is normally activated during mitosis. It is quite possible that epothilone can also act through a similar mechanism.
3-phosphoglycerate dehydrogenase deficiency 3-phosphoserine phosphatase deficiency Phosphoserine aminotransferase deficiency These enzyme defects lead to severe neurological symptoms such as congenital microcephaly and severe psychomotor retardation and in addition, in patients with 3-phosphoglycerate dehydrogenase deficiency to intractable seizures. These symptoms respond to a variable degree to treatment with L-serine, sometimes combined with glycine. Response to treatment is variable and the long-term and functional outcome is unknown. To provide a basis for improving the understanding of the epidemiology, genotype/phenotype correlation and outcome of these diseases their impact on the quality of life of patients, as well as for evaluating diagnostic and therapeutic strategies a patient registry was established by the noncommercial International Working Group on Neurotransmitter Related Disorders (iNTD). Besides disruption of serine biosynthesis, its transport may also become disrupted. One example is spastic tetraplegia, thin corpus callosum, and progressive microcephaly, a disease caused by mutations that affect the function of the neutral amino acid transporter A.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.
Melanotan-1, also called afamelanotide, is a shorter linear analog with a different amino acid sequence and no lactam ring. It has been evaluated in formal clinical programs, while melanotan-2 has not. The two are distinct molecules and are not interchangeable.
No. Bremelanotide is a related but distinct cyclic peptide that reached approved status for one specific clinical indication. Melanotan-2 is a separate molecule with its own sequence and properties. Shared ancestry in the melanocortin family does not make them the same substance.
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.