Melanocortin ligands in laboratory models

Research-use notice: This page is a laboratory mechanism note. It is not medical or veterinary advice, and it does not include personal-use steps. BlueNex Labs materials are research use only. Research-use-only labelling is not a Health Canada authorization and it does not create a Drug Identification Number.

Melanocortin receptors MC1R, MC2R, MC3R, MC4R, and MC5R are G protein-coupled receptors for peptides cut from pro-opiomelanocortin. Alpha-melanocyte-stimulating hormone and ACTH are the reference ligands in that literature. A melanocortin ligand, on this page, is a synthetic sequence studied at one or more of those receptors. For the glossary definition, see melanocortin. The catalogue sequences are not interchangeable, and none of them is a gastric pentadecapeptide or a copper tripeptide.

Five receptors, four shop URLs

Papers often report which receptor subtype a ligand prefers in a binding panel. A preference in one transfected-cell assay is not a catalogue specification, and it is not a reason to substitute vials. BlueNex Labs keeps four live URLs: Melanotan I, Melanotan II, PT-141, and KPV 10 mg. For the overview that separates Melanotan I from Melanotan II, see Melanotan receptor research. For the PT-141 note, see PT-141. For the tripeptide note, see KPV.

Melanotan I is discussed as a linear alpha-MSH analogue. Melanotan II is discussed as a cyclic analogue. PT-141, also called bremelanotide, is discussed as a cyclic analogue related to Melanotan II and studied as a melanocortin-receptor ligand in central-nervous-system models. Related is not identical. The cyclic constraint changes the mass and the conformational ensemble. Confirm the observed mass on the lot you opened rather than inheriting a neighbour's PDF. KPV is Lys-Pro-Val, the C-terminal tripeptide of alpha-MSH. Three residues cannot be filed as a 13-residue analogue.

What the assays measure

Melanocortin methods papers typically report receptor binding, a cyclic AMP or similar second-messenger readout, or a subtype panel across MC1R to MC5R. The endpoint is the receptor under study. This page does not translate a subtype result into a consumer category, and it does not describe these vials as tanning products. The existing Melanotan overview already states that separation. Repeat it in the study file: sequence name, receptor discussed in the paper you actually read, and lot number.

KPV appears in a different slice of the alpha-MSH literature, often as the isolated tripeptide rather than as a full receptor agonist panel. Putting KPV on the same glossary cluster is a reading aid. It does not make the KPV certificate a Melanotan certificate. If the purchasing request says only "melanocortin," send it back for a slug.

Matrix peptides on the same route are a different class

The cellular category hub also lists BPC-157, GHK-Cu, TB-500, and thymosin alpha-1. Those are tissue-matrix or thymosin sequences. What is BPC-157? is the pentadecapeptide note. Copper peptides is the GHK-Cu class. A melanocortin Certificate of Analysis does not document those vials, and their reports do not document Melanotan I, Melanotan II, PT-141, or KPV. Shared navigation is a website structure. It is not a shared molecule.

Sequence strings are part of the record

Melanocortin analogues are long enough, and similar enough in their histidine, D-phenylalanine, arginine, and tryptophan core, that a remembered sequence is a poor identity check. Copy the sequence from the lot report or from the compound guide you actually opened, then compare the calculated mass with the observed mass. A cyclic amide versus a linear chain changes both the mass and the chromatographic behaviour. PT-141 and Melanotan II are the pair most often collapsed by a secondary blog. On this site they are different URLs. KPV does not contain that core as a 13-residue peptide. It is three residues. If the purchasing line says "MSH fragment" without a residue count, it is not yet an order.

Subtype language in papers (MC1R versus MC4R, for example) is a description of the assay, not a second product name. Do not create an internal SKU for a subtype. The vial is Melanotan I, Melanotan II, PT-141, or KPV. The paper you cite can name a receptor. Both facts can be true, and neither fact renames the other. If the institution's receiving template has one field for "class" and one field for "SKU," put melanocortin in the first and the shop slug in the second.

Lot records and domestic fulfilment

Match each vial to its own row in the certificates library when a lot is published. How to read a peptide COA applies here as it does to every other sequence: area percent is purity under a stated method, mass is the identity check, endotoxin is present only if the file includes it. A cropped purity percentage is not a substitute for the sample name.

Canadian laboratories pay by Interac e-Transfer and receive Canada Post Xpresspost. Details sit on the procurement guide. This URL is not a city page. Research use only. Not for human or veterinary use. Confirm the institution's purchasing rules before you order.

Linear, cyclic, and tripeptide are three masses

Melanotan I is discussed in the analogue literature as a linear alpha-MSH analogue. Melanotan II is discussed as a lactam-cyclized analogue. Closing a lactam changes the mass relative to the open chain and it changes chromatographic retention. PT-141 is a further cyclic analogue with its own shop URL. Related structures are still different lots. KPV is Lys-Pro-Val, three residues cut from the C-terminus of alpha-MSH, and it cannot be filed as a 13-residue analogue even when a review uses both names in one sentence.

The four live URLs are Melanotan I, Melanotan II, PT-141, and KPV 10 mg. The comparison that keeps the first two apart is Melanotan I versus Melanotan II. A certificate published for one of them does not document the other three. If the library row is missing, write the absence. A neighbouring product's PDF does not apply just because the class name matches.

Subtype language in a binding panel, such as MC1R versus MC4R, describes the assay. It does not create a fifth catalog SKU. The vial name stays the shop slug. The paper you cite can name a receptor. Both facts can be true. Shared placement on the cellular category beside BPC-157 or GHK-Cu is navigation. It is not a shared sequence, and a melanocortin report does not document those matrix peptides.