This is a working overview of MC1R, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-01-10. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
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.
An antimicrobial surface is coated by an antimicrobial agent that inhibits the ability of microorganisms to grow on the surface of a material. Such surfaces are becoming more widely investigated for possible use in various settings including clinics, industry, and even the home. The most common and most important use of antimicrobial coatings has been in the healthcare setting for sterilization of medical devices to prevent hospital-associated infections, which have accounted for almost 100,000 deaths in the United States. In addition to medical devices, linens and clothing can provide a suitable environment for many bacteria, fungi, and viruses to grow when in contact with the human body which allows for the transmission of infectious disease. Antimicrobial surfaces are functionalized in a variety of different processes. A coating may be applied to a surface that has a chemical compound that is toxic to microorganisms. In the alternative, it is possible to functionalize a surface by adsorbing a polymer or polypeptide and/or by changing its micro and nanostructure. An innovation in antimicrobial surfaces is the discovery that copper and its alloys (brasses, bronzes, cupronickel, copper-nickel-zinc, and others) are natural antimicrobial materials that have intrinsic properties to destroy a wide range of microorganisms. Peer-reviewed antimicrobial efficacy studies have been published regarding copper's efficacy in destroying E. coli O157:H7, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus, Clostridioides difficile, influenza A virus, adenovirus, and fungi.
=== First generation === In-N-Out Burger's first location was opened in the Los Angeles suburb of Baldwin Park, California, in 1948 by the Snyders at the southwest corner of what is now the intersection of Interstate 10 and Francisquito Avenue. The restaurant was the first drive-thru hamburger stand in California, allowing drivers to place orders via a two-way speaker system. This was a new and unique idea, since in post-World War II California, carhops were used to take orders and serve food. In 1951, a second In-N-Out was opened in Covina, California, west of the intersection of Grand Avenue and Arrow Highway. The company remained a relatively small Southern California chain until the 1970s. The Snyders managed their first restaurants closely to ensure quality was maintained. The chain had 18 restaurants when Harry Snyder died in 1976, at the age of 63.
This formed the basis of Australian fair work regulation, even though R v Barger in 1908 quickly struck down the Excise Tariff Act 1906, saying the federal tax power could not be used to indirectly regulate working conditions. In 1956, R v Kirby held that the CCCA was an unconstitutional court because it held both judicial and powers to arbitrate disputes. So, to replace the CCCA, a new Commonwealth Conciliation and Arbitration Commission carried out mediation functions, and the Commonwealth Industrial Court assumed its powers and itself merged into the Federal Court of Australia in 1977.
=== Neonate === To ensure the safety of blood transfusion to pediatric patients, hospitals are taking additional precautions to avoid infection and prefer to use pediatric blood units that are guaranteed "safe" from Cytomegalovirus. Some guidelines have recommended the provision of CMV-negative blood components and not simply leukoreduced components for newborns or low birthweight infants in whom the immune system is not fully developed, but practice varies. These requirements place additional restrictions on blood donors who can donate for neonatal use, which may be impractical given the rarity of CMV seronegative donors and the preference for fresh units. Neonatal transfusions typically fall into one of two categories:
Sources: en.wikipedia.org
== Career == After the break-up of the Beat in 1983 (known as the English Beat in North America), vocalists Dave Wakeling and Ranking Roger decided to continue working together in a new venture. They joined up with keyboardist Mickey Billingham (Dexys Midnight Runners), guitarist Mick Jones (the Clash), bassist Horace Panter (the Specials) and drummer Stoker (Dexys Midnight Runners/the Bureau) to form a supergroup of the UK punk and ska scene. They named the band General Public and were rapidly signed to Virgin Records in the UK and I.R.S. Records in North America. The band recorded and released the album All the Rage in 1984. Jones left General Public part way through the recording process, but he is listed in the album's inner sleeve credits as a group member (although he did not appear in any of the band photographs for the album cover). Jones' replacement, guitarist Kevin White, also played on the album and was also listed as an official group member. White's picture also appeared on the album's back cover. In the UK, General Public had a minor hit with the track "General Public", which reached No. 60 in the UK singles chart in 1984. The single's B-side "Dishwasher" (an instrumental mix of "Burning Bright" from All The Rage) became a surprise Top 40 hit in the Netherlands, after its use as a closing theme tune to the pop radio show Avondspits. Later in the year, the band fared even better in North America, where their second single "Tenderness" was a Top 30 hit in Canada (No. 11) and the US (No. 27).
Age-Related Changes in Expression and Activity of Human Hepatic Mitochondrial Glutathione Transferase Zeta1. Zhong G, James MO, Smeltz MG, Jahn SC, Langaee T, Simpson P, Stacpoole PW. Drug Metab Dispos. 2018 Aug;46(8):1118-1128. doi: 10.1124/dmd.118.081810. Epub 2018 May 31. PMID: 29853471 Free PMC article. Glutathione transferase zeta1 (GSTZ1) catalyzes glutathione (GSH)-dependent dechlorination of dichloroacetate (DCA), an investigational drug with therapeutic potential in metabolic disorders and cancer. ...In samples from livers with the GSTZ1C variant, apparent enzyme kin … Phase 1 trial of dichloroacetate (DCA) in adults with recurrent malignant brain tumors. Dunbar EM, Coats BS, Shroads AL, Langaee T, Lew A, Forder JR, Shuster JJ, Wagner DA, Stacpoole PW. Invest New Drugs. 2014 Jun;32(3):452-64. doi: 10.1007/s10637-013-0047-4. Epub 2013 Dec 3. PMID: 24297161 Free PMC article. Clinical Trial. All subjects completing at least 1 four week cycle remained clinically stable during this time and remained on DCA for an average of 75.5 days (range 26-312). CONCLUSIONS: Chronic, oral DCA is feasible and well-tolerated in patients with recurrent malignant gliomas …
== Structure determination == Initial structures of eukaryotic ribosomes were determined by electron microscopy. First 3D structures were obtained at 30–40 Å resolution for yeast and mammalian ribosomes. Higher resolution structures of the yeast ribosome by cryo-electron microscopy allowed the identification of protein and RNA structural elements. Then structures at sub-nanometer resolution were obtained for complexes of ribosomes and factors involved in translation. After the determination of the first bacterial and archaeal ribosome structures at atomic resolution in the 1990s, it took another decade until in 2011, high resolution structures of eukaryotic ribosome were obtained by X-ray crystallography, mainly because of the difficulties in obtaining crystals of sufficient quality. The complete structure of a eukaryotic 40S ribosomal structure in Tetrahymena thermophila was published and described, as well as much about the 40S subunit's interaction with eIF1 during translation initiation. The eukaryotic 60S subunit structure was also determined from T. thermophila in complex with eIF6. The complete structure of the eukaryotic 80S ribosome from the yeast Saccharomyces cerevisiae was obtained by crystallography at 3.0 A resolution. These structures reveal the precise architecture of eukaryote-specific elements, their interaction with the universally conserved core, and all eukaryote-specific bridges between the two ribosomal subunits.
==== Religion ==== Talarico has been described as a progressive Christian, but has objected to the term, saying he believes not in "a progressive or conservative Christianity" but in a "Biblical Christianity." Talarico has cited his faith and the teachings of Jesus as the reason for launching his political career. He said he was following the commandments to love God and one's neighbor. He said politics is "another word for how we treat our neighbors". Talarico is a critic of Christian nationalism and has called it "a cancer on our religion". He said, "there's nothing Christian about Christian nationalism". In a 2023 guest sermon, Talarico called Christian nationalism "the worship of power—social power, economic power, political power, in the name of Christ". He has said Christian nationalists have turned Jesus "into a gun-toting, gay-bashing, science-denying, money-loving, fear-mongering fascist" and that it is "incumbent on all Christians to confront it and denounce it".
== Clinical Relevance == Despite normally being a commensal organism, C. xerosis has been linked to many different opportunistic infections in humans and animals, including endocarditis, sepsis, abscesses, and osteomyelitis. However, it is possible that many early reports of this bacterium may have been cases of misidentification: a 1996 study found that out of 25 clinical isolates originally identified as C. xerosis, all were actually Corynebacterium amycolatum based on a number of biochemical tests which came back as different from the C. xerosis reference strain. Similarly, there is also evidence that some infections attributed to C. xerosis may have been caused by Corynebacterium striatum. Therefore, it is difficult to determine the actual extent of C. xerosis infections as reported in historic literature; however, modern sequencing and phenotypic analyses have allowed for more accurate identification of C. xerosis in clinical infections.
Sources: en.wikipedia.org
=== Dysfunction of ejaculatory reflex === Ejaculatory dysfunction is when a male is unable to ejaculate properly at the time of sexual climax. Ejaculatory reflex dysfunction is one of the leading causes in male infertility. Some conditions in which ejaculatory reflex dysfunction is observed is multiple sclerosis, diabetic neuropathy, spinal cord injuries, or side effects of certain medications. Examples of dysfunction of ejaculatory reflex include:
The latter programme took place in Vichy, and was spread over three weeks, allowing Wenger to be able to put Frantz's teachings of isometrics into practice. In 1981, he received his manager's diploma in Paris.
The new 24th district, centered on Dallas Fort Worth International Airport in the heart of the Dallas–Fort Worth metroplex, encompasses the suburbs north of Fort Worth and Dallas, including Grapevine, Bedford, North Richland Hills and Southlake in northeast Tarrant County, and the wealthy Park Cities north of downtown Dallas, as well as the neighboring Knox Park and Lower Greenville neighborhoods and most of north Dallas (including Preston Hollow) in Dallas itself and the Dallas County suburbs of Farmers Branch and Coppell. Due to redistricting, the district has two incumbents, Republican Beth Van Duyne, who was re-elected with 60.3% of the vote in 2024, and Democrat Julie Johnson, who was elected with 61.9% of the vote in 2024 from the old 32nd District. Donald Trump won 57.1% of the vote in this affluent district, which also gave Ted Cruz 54.6% of the vote that same year against Democrat Colin Allred, whom Johnson succeeded in Congress. Johnson has since decided to seek reelection in the newly redrawn 33rd district (see below).
Lazy eye Positive Babinski sign Generalised convulsion Cortical visual impairment Involuntary rhythmic muscular contractions and relaxations Swallowing difficulties Dystonic movements Elevated plasma acylcarnitine levels Increased deep tendon reflexes Increased muscle tone Infantile spasms Involuntary, rapid, rhythmic eye movements Optic-nerve degeneration Stroke Supranuclear gaze paralysis Very rare:
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.